Rare Australian 50c coin printed with error. The Australian 50c coin minted in 1988 contains a significant error by the Royal Australian Mint. During 1988, it was decided 50c coins would commemorate the 200th anniversary of the arrival of the First Fleet, with the standard coat of arms being shelved.However, some coins slipped through the cracks, with the standard coat of arms printed on the coin as well as the 1988 date on its back. Claiming there is only two of its kind. "A mouth-watering opportunity to secure truly great decimal rarities. One of the two known 1988 50c coat of arms proofs, ". As is customary, the creation of a special one-year-only 50c commemorative meant the standard Coat of Arms 50c was not struck for circulation and was naturally not included in the proof or mint sets of that year either. Therefore, no 1988 coins with a coat of arms should exist. However, the "genuine mule error" was created with the accidental union of mismatched obverse and reverse sides.