As with many other denominations, the sixpence's obverse and reverse designs were updated in 1887. The sixpence's reverse design ultimately received two major updates as the first new reverse (a shield) was similar enough to the half sovereign's design that, coupled with the similar sizes of the sixpence and half sovereign, there were attempts to gold plate the new sixpences and pass them off as half sovereigns (Gouby, http://michael-coins.co.uk/sx1887%20JH%20var.htm). As a result, the shield obverse was short-lived.
Two different obverse and two different reverses were used for the 1887 shield sixpences: on Davies obverse 1 the designer's initials JEB are on the truncation of the portrait and on Davies obverse 2 the designer's initials JEB are below the truncation of the portrait and on Davies reverse A the tail of the Q in QUI is missing and the loop above the buckle between the date is incomplete while on reverse B (not recorded by Davies) the tail of the Q in QUI is visible and the loop above the buckle between the date is whole.
Not all obverse and reverses were paired with each other: 1+A coins (Davies 1150) exist, Davies 2+A coins (Davies 1151) exist and 2+B coins exist. 1+A coins are quite scarce, 2+A coins are common, 2+B coins appear to be mostly or entirely proofs and 1+B coins are not known but may exist.
In 2003 the Royal Australian Mint struck a commemorative $1 coin to commemorate 100 years since women's suffrage was achieved in Australia. Two slightly different reverse designs were used to strike these coins: the reason for the change is not known but it is assumed that the first design was prone to die deterioration or cracking and so an improved design was used to strike the balance of the mintage.
The differences between the designs are subtle: one on design the letters CEN touch, the RA run into each other and the gap between the rim and the women is small (the so-called large reverse) and on the other design the letters CEN are spaced out, the RA touch but do not run into each other and the gap between the rim and the women is large (the so-called small reverse).
Neither variety is rare and the split is approximately 70% large reverse and 30% small reverse.
Note Printing Australia has produced test polymer notes on a number of occasions: these notes bear no denomination but are believed to be designed to show-case the polymer banknote technology. A number of these notes are known in private hands, though their intended recipients are most likely overseas central bank or government employees. Various designs have been produced over the years.
NPA test note designs and sales
Design
Serial Numbers known
Sales
Don Bradman/Melbourne Cricket Ground
AA0031 499
Downies sale 351, February 2024 (AA0031 499)
Rembrant/Picasso (plain window)
AA 03 002678
Rembrant/Picasso (Rembrant window)
AA 04 002569 AA 04 002570 AA 04 002571 AA 04 002572 AA 04 002600
A number of upsets/rotated dies are known in Australia's predecimal coins - certainly slight upsets can be found much more frequently than in the decimal series but large offsets are still uncommon.
The coinage of the Andman Islands off the East coast of India was unusual in that while the tokens bore portraits of Queen Victoria, the tokens were also holed - outside of patterns, all tokens had a central hole.
One of the rare, unholed patterns has an 1861 reverse with the 1866 portrait: in 1861 the tokens were struck with William Wyon's early Straits Settlements portrait of Queen Victoria while the the 1866 tokens were struck Leonard Wyon's British India portrait of Queen Victoria, and in the British Museum is an 1861-dated token with the 1866 portrait: https://www.britishmuseum.org/collection/object/C_1935-0401-12273
The circumstances in which the mule token were struck are not known - the 1935 in the British Museum item number suggest that it was acquired in 1935: given that it was bequeathed to the British Museum by Thomas Bryan Clarke-Thornhill who died in 1934, this seems almost certain. Clarke-Thornhill served as a secretary in Diplomatic Service from 1881 to 1900 and served in China in 1900 (https://www.britishmuseum.org/collection/term/BIOG105767). Although his service in the East was well after the tokens were struck, as a collector he may have acquired the piece during his work overseas.