1975 Double Headed Australian Coins
Double-headed and double-tailed coins are rare errors in Australia, so it is unusual that there are seven known double-headed 1975 coins across six different denominations.
Unusually, a 1c, 2c, 5c, 10c, 20c and 50c all struck as double-headed proofs are known. They are struck in coin alignment, and the 2c piece was almost certainly struck at the Royal Australian Mint rather than the Perth Mint. It is not known if there were in a plastic proof case or not as they were sold individually. While double-headed or double-tailed coins are rare, proofs are even rarer. The six coins were sold as lots 88 to 93 in Noble auction 114 in March 2017.
A circulation 1975 1c piece is also known. It is also struck in coin alignment and has been listed lot 131 in Noble auction 95 in November 2010 and lot 93 in Noble auction 114 in March 2017.