2008 20 Cent Varieties
In the early 2010s it was noticed that a small number of 2008 Australian 20c pieces had a small gap between the wave and the playtpus' head, similar to the wave gap used as a mintmark on 1966 20c pieces. While it is a part of the design that is subject to die fill, it was realised that it was likely a genuine variety as the 2008 Wedding Set coins all exhibited the wave gap. With a mintage of just 3,278 sets, the wave gap was unlikely to be due to die fill. It seems likely that the Royal Australian Mint accidentally deployed a Wedding Set reverse die for the production of circulation coins, though it is unclear why such a design change was made for the Wedding Set coins.
While the wave gap variety makes up a very small percentage of the total mintage, with 132,900,000 2008 20c pieces struck, there were approximately 1,000,000 wave gap coins struck.