The term 'coin hoard' conjures up images of piles of coins buried somewhere in the Spanish Main by buccaneers ready to be collected on their return to England or Port of Spain. In reality coin hoards are far more mundane but they still stir the imagination of coin collectors because of the provenance they lend a coin and the possibility of getting a coin that has been 'untouched' for years and is new onto the market. In the USA coin hoards, while not common, are far more prominent in the market than here in Australia. There are many well known US coin hoards such as the Binion Hoard, the Redfield Hoard, and the Mid-West Mega Hoard. These hoards contains thousands, tens of thousands, and in the case of the Mid West Mega Hoard, millions of coins. The mystique associated with these hoards has even lead to the major third party grading companies noting the provenance of coins from major hoards on their coin holders.

Coin hoards in Australia are not so common as elsewhere, but they do occur. There are two well known hoards that I know of, and I am sure there are many more. The first is the Reserve Bank 'hoard' (or collection or accumulation). In 2005 the Reserve Bank of Australia decided that the reasons for maintaining a physical stock of gold had passed, and liquidated 5,850 Australian Sovereigns, Half Sovereigns, Adelaide Pounds, and some foreign gold coins. These were auctioned by Downies and caused a major influx of coins into the market. Another well known hoard is the 'Vienna Hoard' of the late 1980's. Many rolls of Australian florins and shillings struck in the mid 1940's were hoarded by an Austrian immigrant jeweller prior to the debasement of silver coinage to 50% silver. More than 5000 uncirculated silver coins were released onto the market from this hoard in the late 1980's by a major Australian coin dealer.

Coin hoards can have an interesting effect on the coin collecting market and hobby. For example, when the US Federal Reserve disposed of millions of uncirculated Morgain and Peace dollars in the 1960's it single handedly spawned an explosion in the interest in coin collecting in the USA. Other hoards can have a significant impact on the value of existing coins on the market. For example, in 1984 only 13 Athenian Decadrachms were known to exist, however in that same year a hoard of 14 of the same type were recovered in an archaelogical dig. They were in superior condition to the already known examples and instantly devalued the coins already held by collectors. A less well known hoard (or perhaps accumulation) of Australian coins were gathered by an Australian collector who collected items from 1912, including a large number of high grade 1912 3d's. When these entered the market they immediately increased the supply of high grade coins of the type rendering catalogue values irrelevent.

One last note, and perhaps a controversial one, is a warning to the collector about the marketing techniques used by some coin dealers. Playing on the romance and mystique behind the term 'hoard' some dealers are forever discovering 'hoards'. Even if these hoards are in their very own (clearly overstocked) coin vaults! Beware of being taken in by such marketing, often items in these so called 'hoards' are available elsewhere and at a lower cost. As always do your research.

Another dollar coin issue in the Inspirational Australians series from the Royal Australian Mint, the Steve Irwin Dollar. Our very own Crocodile Hunter who died tragically in 2006 is forever inscribed onto this new dollar released July 6th 2009. The 25 millimetre aluminium bronze dollar is only available on a special descriptive card in uncirculated condition and will never be seen in circulation.

Steve was a truly inspirational Australian with his larrikin personality striking a chord with many Australians through his award winning wildlife documentaries. His passing was truly a sad day when he was hit by a sting ray barb whist filming off Port Douglas in far north Queensland in 2006. Steve's passions have continued through his widow Terri and their children Bindi and Bob and their work at Australia Zoo and the charity Wildlife Warriors.

This Crocodile Hunter 1 dollar coin was designed by Caitlin Goodall and depicts Steve's portrait surrounded by some of his favourite wildlife, a Koala, Crocodile, Snake and Galapagos Tortoise in rain forest foliage. This unlimited mintage issue at $12.95 is sure to be popular both here and overseas with Steve Irwin Day to be celebrated on the 15th November.

For accurate coin mintage data please see the 2009 Australian 1 Dollar Coin Mintages table.

Before I look at the answer to this question I should define what a 'top pop' coin is. PCGS and NGC define the number of coins of a particular type that they have graded as the 'population'. A top pop coin is simply the best or equal best coin of that type graded. It is important to realise that even though PCGS or NGC say they have graded (for example) 100 coins of a particular type that there almost certainly are not 100 different coins of that type graded. The reason? Sometimes people will believe that a coin is undergraded by the third party grading company and 'crack out' the coin (break it from the slab) and resubmit it. This happens quite a bit with American coins because the difference of just one MS point in grade for some coins can mean thousands or tens of thousands of dollars of difference in value.

OK back to the question in hand, is now the time to buy top population slabbed Australian coins? The answer? A definitive maybe. Personally I take each coin on a case by case basis and in my own mind I split up top population coins into three main areas. Firstly, the common date coins which have large graded populations, secondly less common date coins with large graded populations, and less common date coins with low populations. I'll be talking about the PCGS population report a bit here, so it might be worth taking a look at it so you can see what I am talking about.

1. Common Dates with Large Populations

I do not think it is worth paying much of a premium for top pop coins with large populations and multiple coins at the highest grade. The main reason is that the supply of top pop coins is greater and the likelihood that the population at the top levels will increase or even be surpassed is pretty high. I'd nominate the second half of the 1950's and all of the 1960's as areas where I wouldn't want to pay too much of a premium for top pop coins. 1940's US minted silver coins is also another area where I wouldn't want to pay too much of a premium either. Of course there are some exceptions to this, 1956 shillings and florins are harder coins for example and may well be worth the investment. The key thing with common dates with large populations is that if you can grade yourself you may be better off submitting your own coins rather than paying a premium for already slabbed coins.

2. Less Common or Tougher Dates with Larger Populations

Statistics suggest that if a less common date (or just a harder date to get in a nice grade) has a larger population then the current grade distribution will be approaching that of the total non slabbed population. In this case I'd suggest paying the sort of premium that you'd be happy to pay for any sort of keydate or semi keydate coin. Evaluate recent sales results (auction results, eBay past sales, and the Bluesheet can be helpful here) and pay in accordance with these results. If you're lucky the larger population of the coin will allow you to evaluate the going rate for such a coin.

3. Less Common Dates with Small Populations

These coins are the toughest to decide whether paying a premium for a top population coins is worth it or not. Before you decide you should really familiarise yourself with the coin in question to get an idea of the general quality of non slabbed uncirculated coins on the market. A good example may be the 1948Y penny. It's a hard coin to find in uncirculated grades and those that you do find are not very well struck up (like a lot of Perth Copper) and can be baggy. A graded population of just 4 coins, one in MS62BN and 3 in MS63BN means that if you want a MS 1948P penny then you've only got a few coins to choose from. And MS63BN doesn't sound like a great grade either. However, I can tell you that this grade for this coin is simply exceptional and would be very tough to surpass. Personally I'd be happy to pay a premium for a coin in this grade.

A flip side to this is the 1942I half penny. There are only 4 coins graded of this type with the top 2 coins being MS64RB. With a bit of effort and some time I believe you would find a similar coin that is not slabbed. Couple this with the fact that I dont believe this coin is a particularly popular coin means that I wouldn't want to pay too much of a premium for a top pop 1942I 1/2d that is already slabbed.

Conclusions

As always this is just my opinion and please dont go taking any of it as investment advice. However, I believe it's a reasonable place to start when you're comtemplating the purchase of a top pop slabbed Australian coin. As always educate yourself as much as possible before such a purchase, consult the catalogues, past auction results, and look at as many coins of the type as possible. It's your money and it may well end up being your coin, so make sure you get the coin you deserve.

If you're like most of us you probably have a jar or moneybox or dish lying around where you drop your excess change in. You might do this as a form of saving or just for convenience when your pockets or wallet get heavy. Then the jar starts to over flow or the money box gets full and you have a dilemma. Do I spend it or bank it?

Spending:
Retail shops do have a limit on the numbers of coins you can hand over to pay for a sale. They may refuse the cash if you try to hand over too many coins or small notes for a purchase. The limits are outlined below as per the Australian Currency Act.

Denomination	Quantity
1c & 2c	Now removed from circulation: Maximum of 20 cents
5c, 10c, 20c & 50c	Maximum of $5
$1, $2, $5 & $10	Not exceeding ten times the face value, inclusive ie a maximum of $100 for $10 notes (10 x $10)
Any other denomination	To any value

We're really picking up now with the sheer numbers of dollar issues minted by the RAM. Key military themes emerge over these years and the following few with the VC dollar a hugely popular coin, you'd be lucky to pick up one of these for under $200 with both packaging types having cv's of $285-$325.

2000 was a very busy year with both the Olympics and Millennium celebrations. The value of the 2000 mint and proof year sets is high because of the high volume of visitors in the country who took their purchases back to their home countries.

A couple of VIP issues for these years. These coins are the same so only those with packyboxitis should look into this further. The HMAS Sydney II launch folder is just a regular S mintmarked folder but with special VIP launch printing on the folder. The Federation Special VIP release Proof Set for 2000 is also just an added signed (by the then mint controller Graeme Moffatt) certificate within the packaging.

Year	Description	Type	Mint Mark	Composition	Notes	Mintage
1999	International Year of Older Persons	Circulation	None	AlBr	Circulation	29,218,000
	International Year of Older Persons	Circulation	None	AlBr	PNC	56,065
	The Last Anzacs	Circulation	C	AlBr	Mint Your Own RAM Visitor Press, Dealer and RAM Sales	126,161
	The Last Anzacs	Circulation	S	AlBr	Portable Press Sydney Royal Easter Show, Dealer and RAM Sales	53,286
	The Last Anzacs	Circulation	B	AlBr	Portable Press Brisbane Show, Dealer and RAM Sales	33,634
	The Last Anzacs	Circulation	A	AlBr	Portable Press Adelaide Show, Dealer and RAM Sales	28,681
	The Last Anzacs	Circulation	M	AlBr	Portable Press Melbourne Show, Dealer and RAM Sales	49,841
	The Last Anzacs/Year of Older Persons	Circulation	C/None	AlBr	Dual Set	33,922
	The Last Anzacs	Proof	None	.999 Silver	Silver Proof Interrupted Reeding	25,000
	International Year of Older Persons	Circulation	None	AlBr	Koala Baby Mint Set	35,718
	International Year of Older Persons	Circulation	None	AlBr	Mint Set	70,067
	International Year of Older Persons	Proof	None	AlBr	Proof Set	28,056
	International Year of Older Persons	Proof	None	AlBr	Koala Baby Proof Set	6,707
2000	Mob of Roos	Circulation	None	AlBr	Circulation	7,592,000
	HMAS Sydney II	Circulation	C	AlBr	Mint Your Own RAM Visitor Press	86,900
	HMAS Sydney II	Circulation	S	AlBr	Sydney Mintmark -coins pre-struck in Canberra	49,022
	HMAS Sydney II	Circulation	S	AlBr	Coin Launch Folder	2,922 were originally minted. Of these less than 300 were given out at the launch and the rest destroyed.
	Victoria Cross Centenary	Circulation	None	AlBr	VC Folder	49,979
	Victoria Cross Centenary	Circulation	None	AlBr	PNC	48,830
	The Last Anzacs	Circulation	None	AlBr	PNC (same coin as 1999 Last Anzacs but dated 2000)	47,830
	Olymphilex	Circulation	C	AlBr	Edge Lettered "Canberra", Issued at Olymphilex Trade Fair	72,573
	Olymphilex	Circulation	S	AlBr	Edge Lettered "Sydney", Issued at Olymphilex Trade Fair	98,567
	Mob of Roos	Circulation	None	AlBr	Koala Baby Mint Set	27,118
	Mob of Roos	Circulation	None	AlBr	Mint Set	106,394
	Mob of Roos	Proof	None	AlBr	Proof Set	64,904
	Mob of Roos	Proof	None	AlBr	Koala Baby Proof Set	15,557
	Mob of Roos	Proof	None	AlBr	Same as Proof Set but includes signed numbered certificate -Celebrating Federation (VIP)	100
	HMAS Sydney II	Proof	None	.999 Silver	Silver Proof Interrupted Reeding	12,150
	Mob of Roos	Circulation	None	AlBr	$1/10c MULE , struck with 10c obverse die	unknown, estimates 6-7,000

We've recently had our own completely 100 % PVC free coin album pages designed and manufactured, you can read about these over at the Purple Penny Coin Accessories website. Our pages are 100% polypropylene, which is a naturally pliable plastic that is very stable and contains no softeners that can leach out onto your coins. They are not the only polypropylene coin holders available on the market, nor are polypropylene and PVC the only materials that are currently used to make coin album pages.

Because of the current interest in the market in storing your coin collection safely (perhaps in no small part to this blog) some album pages are currently being sold as "archival safe" that clearly are not. We know of one page type being sold as archival safe and acid free that is nothing more than a common PVC album page. In the interests of working out what your coin album pages are made from I thought it might be worth discussing the main types of album pages you can find.

Polypropylene Album Pages

Currently the three main types of polypropylene album pages you can find on the market are the Purple Penny album pages mentioned above, Ultra Pro album pages, and BCW album pages. The BCW and Ultra Pro album pages are made from quite thin material and are not very rigid. The Purple Penny pages are made from thicker material and are of comparable rigidity to PVC album pages. Lets look at some of the physical characteristics of polypropylene.

Colour: Colourless
Odour: None
Elasticity: Moderate
Friction: Low

Essentially polypropylene album pages are crystal clear, the plastic is quite 'slippery' to touch, and the material shows good 'stretching' before it will tear. A key thing to note is that polypropylene pages are odourless.

PVC Album Pages

By far the most common album pages on the market, these pages are what you most likely have in your coin albums (shame on you!). They are typically made from thick material (up to 0.2mm thick), are quite stiff, and hold even heavy coins very well. A key thing about PVC to realise is that in it's native state it is not 'soft' or 'flexible', it is in fact a very stiff material with a high modulus of elasticity. Did you know that almost all water pipes and drain pipes in the modern home are made from PVC? Yes the hard brittle white plastic pipes you see on building sites are PVC. So how can soft, flexible coin pages be made from PVC? By the addition of softeners, most typically pthalates. Lets look at some properties of PVC.

Colour: Colourless
Odour: Strong
Elasticity: Limited without softeners, good with softeners
Friction: moderate, can be 'tacky'

PVC album pages are colourless, and quite 'stretchy' and soft. They are not difficult to tear especially when trying to get a 2x2 into an undersized pocket. A key indicator of PVC album pages is the odour. If you've ever opened a new inflatable pool toy you know what this smell is, it is very distinctive and is a combination of the PVC itself and the added softeners. Another indication of a PVC page is in the marketing of the page itself, if it is described as 'soft' then it's almost certainly a PVC page.

Mylar Album Pages

There is one type of album page available that comprises of an outer PVC sleeve into which Mylar (trade name for PET plastic) inserts are placed which hold the coins. Coin holders made form Mylar are distinctive, mylar is quite hard and brittle. It is however odourless and completely inert, and makes an excellent coin holder. SafeT Flips are made from mylar and are an excellent coin holder that is very popular on the US market. One can only wonder why a manufacturer chose to put perfectly good mylar coin holders into a PVC sleeve.

HDPE Album Pages

One last type of album pages you may find on the market are blow moulded type album pages that snap together to hold various types of coin holders. This is the sort of colourless plastic you'll find in toy packaging that protects the toy while allowing the greedy child to see exactly what they want. HDPE coin album pages available in Australian include pages to holder coin slabs and Eagle 2x2 coin holders. HDPE can be a colourless mechanically strong material, but when used to make album pages it is hard with limited flexibility. This is why it is generally used on pages that hold heavier rigid coin holders.

Conclusions

Firstly, don't believe the hype. Either from us or from others. Read, educate yourself, and draw your own conclusions. If a seller says a page is PVC free or 'archival safe' don't take their word for it, look out for that distinctive odour, that 'tackiness' that PVC coin pages show. If you want to know what a page is made from ask the supplier of the page, if they've got nothing to hide they'll tell you. Don't be fooled by buzzwords like 'acid free'. Use your eyes, your nose, and your hands to make your own judgements, and make sure you get the truth about the page. It is, after all your coin collection, and it deserves to be stored in stable, inert coin albums and pages that will not affect the quality of your coins.

To help you catch up on the continuing story, have a quick read about the pre-release details of the Master Mintmark Dollar. No one was certain what this release was going to be.

Last weekend it all happened. Friday morning the Royal Australian Mint anticipated a crowd of visitors and hired extra security for the event prior to the doors opening at 9am. There had been speculation there would be campers to gain their spot in the queue early on Friday morning. Sadly this wasn't the case and this story unfolds thanks to fellow numismatist, the first RAM attendee to this event Goldseeker. The crowd of few were let loose at 9am who paid their $12 at the till per coin and proceeded to the queue to mint their coin. Obviously due to the short notice to collectors and other numismatic activities last weekend the crowd for the entire event was minimal. Apparently the queue to mint coins was never longer than 10! The counterstamped Master Mintmark coin was available to (press the button yourself) mint for 4 days only at the RAM.

The Counterstamp Mintmark of mention in this post is a confusion in itself. The coin available to press by RAM attendees was a 2009 Mob of Roos one dollar with a special Kangaroo mintmark that consists of a C with a kangaroo hopping through it. That's not the real special bit though. The extra special addition was that of a C counterstamp below the D of dollar on the reverse of the coin (seen on bottom image). These coins with the counterstamp are proving to be a scarce release with dealer sales already looking at the $30-$50 mark, mintage was a tiny 6,500 coins.

The master mintmark coin is non-counterstamped version of this. It's a 2009 mob of roos one dollar with a C and a kangaroo hopping through it. This coin is readily available with a mintage of 23,758.

Well known and respected Australian numismatist, Peter Andrews, has a very interesting website we've written about before, The Sandpit. He's just popped up a new article he's entitled To Slab or Not to Slab - Part 1 Grading. In it, Peter has summarised a system proposed in the book called "How to Grade US Coins" by James Halperin. Halperin is an established figure in the US coin market and is still a director of the huge auction house Heritage Auction Galleries.

The system proposes that the grade of an uncirculated (or MS) coin can be determined by 4 factors:

1. Surface Preservation
2. Strike
3. Lustre
4. Eye Appeal

It then goes onto suggest that by rating an MS coin on a scale of 1 to 5 for each of these factors and adding the total (with double weight given to surface preservation) that you can use the result to determine the MS grade of a coin.

I haven't read the book Peter used to develop his article, but it certainly makes a lot of sense. It's well worth the read and I'd strongly recommend anyone serious about grading of coins and with an interest in slabbed Aussie coins should head over to his site and take a look.

I recently visited the Melbourne and Brisbane ANDA shows and always have varying journey's around the country touring coin shops and Auction viewings. This is my hobby, it's what I do and what I love. I'd like to appeal to dealers and sellers just to think about their methods of showing their coins to potential purchasers.

From a buyers point of view:
A lot of dealers have their stock in books that are just falling to pieces. Broken albums, torn pages and daggy old 2x2's are not getting them any sales. I see adhesive 2x2's that have come apart and the adhesive is stuck to the coin surface -I'm not going to buy that coin. I see 2x2's that have aged and the mylar has stretched and become cloudy making it impossible to accurately view the coins grade or condition. I see coins that have a green tinge to them from being housed in pvc pages for far too long-I'm not even going near that coin to buy! I see stock in secure cabinets that's a great idea but often it's bunched up and not well labelled. This is very difficult to view and easier to just walk away and not bother. As a buyer I want to have freedom to view a coin accurately. A well lit environment, a clear holder is what I need to make my decision on grade and it will get the dealer their sale. After all that's what they are there for!

This is my marketing message to sellers:
The smart move is to make your product as saleable as possible. Show the customer that you've cared for the coin, after all it's soon going to be theirs. Make it easy for the customer to find and view your product. Have your stock books sorted and labelled, have your stock in clean and neat staple 2x2's in non-pvc pages. Have your one off pieces in a system that suits you, eagles, capsules, slabs there is such a variety out there to choose from. If you're going to house stock in locked cabinets then arrange and label it well. Have the staff available and be willing to open the cabinets up and show off your coins to potential customers. It's going to make the sale, that's a simple rule for marketing.

The Melbourne ANDA Coin and Banknote Show for 2009 was held on Saturday and Sunday 4th and 5th July. The venue for this years show was the the Caulfield racetrack and not the Tennis centre where it has been held previously. This was a bit out of the way for us out-of-towners compared to the Melbourne Tennis Centre right in the city but we found it with the help of our friendly GPS.

What a great venue! Right beside the racetrack with plenty of free parking and right beside the train station. There was tons of room inside for all exhibitor tables and more. Lighting was an issue they'll need to address for future functions. Some tables away from the windows were very poorly lit making viewing difficult. There were plenty of show attendees but it didn't seem at all crowded due to the large expanses of the venue. With heating and good (but expensive) food on offer I would certainly go again but maybe with a packed lunch. We'd rather spend the money on coins!

A wide array of dealers were in attendance. It's good to see them from all over the country making an effort to attend. There were a number of local Melbourne dealers attending too (with a few notable exceptions) with lots and lots of stuff to view. Frequent show attendees present were Steele Waterman Coins, VP Coins, Klaus Ford Numismatics, Prospect Stamps and Coins, Sterling and Currency, Int Numis, Coinsearch, JPW Coins, Monetarium Adelaide, and Edlins just to name a few. Local dealers such as Klaus Ford and Peter Strich loaded up plenty of extra stock that others aren't able to bring due to airline restrictions. There were also the regular auction vendors in attendance Roxbury's, Downie's and IAG. A favourite of ours is Drake Sterling with their usual array of tempting PCGS slabbed coins. It's interesting to note that Drake Sterlings' idea here is quality and not quantity and cabinets of slabbed coins do look appealing.

The Perth Mint showed off their impressive array of recent issues. It's great to see them make an effort to attend. The RAM didn't attend this show with their portable press, a real disappointment for show-goers. We believe there was a representative from the RAM in attendance. Kudo's to one dealer who kept offering us a chocolate coin while we perused his stock. Perhaps we'll eat it next time.

Like the last Brisbane Coin and Banknote Show the ANDA released an overprinted 2009 mintset that was available only at the Melbourne show. The ANDA logo was printed on the slip cover this time, unlike the Brisbane Show which was just a sticker on the outer cover. These were limited to 2 sets per ticket holder. The other ANDA special release was a limited edition Perth Mint gilded Kookaburra with the ANDA logo on the box. Every hour show organisers would make an announcement over the PA system of the winner of the lucky door prize - sadly neither of our names came up. Vic Power of VP coins all the way from Queensland was also giving away his show special token for collectors spending $20 or more at his table, a nice token from Vic.

Overall a pleasing event to attend although Melbourne could have put on some better weather.

Question:

Hi,

I hope you don't mind me emailing you. I was at the shops the other day and in my change I got give a 1973 50c with a 'V' stamped on it, to the right of the queen's head. I was wondering if this was a real mark and its purpose. I thought maybe it had something to do with the Vietman war (being 1973), or maybe the state of Victoria, or maybe it's just someone with nothing better to do stamping the letter V onto it!

Any thoughts?

Thanks,

Answer:

Hi, Thanks for the email and for reading our weblog. Sadly these sorts of marks are what is known as post mint damage. They are applied with punches and hammers and given that it doesn't destroy the coin they'll keep circulating without most people even noticing the mark. Well done on noticing it yourself! Someone mentioned to me once that people in metal working shops would do this sort of thing to help train new apprentices and so on. I've also heard one other theory that vending machine makers and service agents mark coins so they can test out the coin feeding mechanisms and hoppers of their vending machines.

Yours is the first 50 cent I have seen or heard of marked in such a manner, typically $1 coins are the most common. As to it's worth, I have seen marked coins like this go for a little above face value on eBay but with listing fees and final value fees I wouldn't list it any time soon. It might be worth keeping as a curiosity. I keep them and as I type this stuck to the edge of the monitor in front of me there's a $2 coin that someone has punched 'sunglasses' onto the aboriginal on the reverse of the coin.

Please have a nice day,

The Australian Threepence Blog Team

Please note that in the interest of anonymity we always remove names so that we can share our questions and answers with everyone.

Question:

I have a double headed 20c in fair condition. It has 1968 on one side and 1969 on the other. Is it of any particular value?

Answer:

Hi, Thanks for reading our blog and thankyou for your question. The coin you speak of is almost certainly a forgery of 2 sides cut and joined. This is often done as a joke so you can win the coin flip "heads or tails?" Can you see any evidence of this on the rim?

If you can't see that it's been tampered with then the next step is to weigh the coin accurately, it should weigh 11.31g. If there is any difference there it is almost certainly a fake.

There are some genuinely head/head or tail/tail error coins out there. For these coins to be made there has to be some "fiddling" going on with the presses at the mint for the "special" coin to be struck. Often these coins are in top grade. A genuine coin will always be upset 180 degrees, this is how the press works with the wrong die on the opposing side. Is your coin upset 180 degrees? (Hold the head upright and spin the coin around. Is the other other head upright straight or uside down -hence the 180 deg?) If it is genuine then these coins may sell for up to a couple of thousand dollars each.

Your coin being of 2 different years also rings alarm bells as the reverse die for the previous year would have been well and truly put away at the Mint making it much more difficult for the press to be tampered with to produce this coin. It is most likely a backyard machining and gluing job.
Happy hunting,
The australian-threepence.com blog team