Dating an australian
Initially only a few were found but in the last few years more and more have surfaced leading to the idea that there could be thousands of these error coins in circulation.As the word trickled through to collectors more and more coin noodlers fossicked bulk lots searching for the coin with 2 heads.
The second strike on those coins is an off-centre duplicate of the first, obverse to obverse and reverse to reverse.
When you do find one don’t jump for joy too hastily, a double header coin is easily faked. Double headed coins that have been found are all dated 2007 on both sides. The opposing side will be struck exactly 180 degrees upset or rotated.
Boring or grinding out the tails side of a coin, grinding down the tails side of another and joining the two together is the most common type of fake. If two coins have been joined it’s not likely the weight will match a genuine coin. A small tolerance is within specification but if the weight is grossly higher or lower then you might not have a genuine error. Having different dates is an indicator the error is a fake. This means one side will appear completely upside down. Look closely at the rims on both sides to see if there is indication that 2 separate coins have been joined.
It is worth considering what the other coin this error was struck against might look like.
It will have a crescent shaped indentation on the reverse, and within that indentation there might be a partial brockage impression of the obverse of this coin.