I gave them the "Toggle Test"
Both stamps look identical, only difference I could spot, was the full stop
after "Australia" was a little larger. (Far from being a variety)
Have you checked perforation guaging? (The Perforation Pin diameters differ)
Bib Stanley Brit Comm 1993 Part 1
Just a thought
perhaps your memory is playing tricks
Both your stamps are Varieties, the original stamp was chocolate