We will probably never know. That type of error might have been noticed after the first day of minting.
There were a total of 243,340 1888 Double-Florins minted.
There were 188,000 1932 Australian Florins minted.
Rare is a relative term. Most New Zealand Florins were minted in quantities greater than 1 million. New Zealand Florins of which there were fewer than 200,000 minted include the years 1936, 1942, 1944 and 1963. There were 300,000 1946 "Flat Back" Florins (the Kiwi has a flat back) of a total of 1.2 million Florins minted in 1946. What might be considered rare are the Proof Florins. In most years they were minted, there were 200 or less minted.
There were no 1927 British Florins minted for general circulation. There were 15,000 Proof FDC 1927 Florins minted featuring the new reverse design.
The New Zealand Florin was first minted in 1933 and last minted in 1965. During this period, Florins were not minted in 1938, 1939, 1952 and 1954 to 1960 inclusive.
There were sufficient Florins already in circulation without having to mint any more.
There were no Australian Florins minted until 1910.
With the possible exception of traders tokens (with the traders business name on them), there were no "Australian" Florins minted prior to 1910. Any Florins circulating in Australia prior to 1910, would have been British Florins.
There were no New Zealand Florins minted prior to 1933.
With the possible exception of traders tokens (with the traders business name on them), there were no "New Zealand" Florins minted prior to 1933. Any Florins circulating in New Zealand prior to 1933 would have been mostly British Florins and perhaps some Australian Florins.
The first British Florins were minted in 1848 as a tentative step towards decimalisation.
A British sterling silver Double Florin (Four Shillings), was only issued from 1887 to 1890 and abandoned possibly due to its size and weight. A British sterling silver Double Florin (Four Shillings)(Victoria)(depending on the year), uncirculated and in absolute mint condition could fetch up to £130 GBP. If it has been circulated but still in good condition, it might fetch up to £12 to £60 GBP. A reputable coin dealer will be able to give a more accurate valuation.
With the possible exception of traders tokens (with the traders business name on them), there were no "New Zealand" Florins minted prior to 1933. Any Florins circulating in New Zealand prior to 1933 would have been mostly British Florins and some Australian Florins.