Interesting. It could be argued that ghosting on a 1967 penny is interesting precisely because it's not often mentioned even though the coin is extremely common.
I checked the latest edition (2016) of Michael Freeman's book on British bronze coinage (the Numista Library has the third edition from 2006). He only mentions ghosting briefly in the introduction and under each ruler (briefly again) from Victoria to George V.
However, several of his pictures of the George VI–Elizabeth II pennies seem to show some slight ghosting. Perhaps @Moneytane could confirm that since he has the same book. The fourth edition is a reprint with appendices by Chris Perkins; the photos are not the best though they do the job of showing re-engravings and other such varieties.
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