My cat has two 6 toed feet on rear legs

[Karen]

She's officially a polydactyl! It's not that rare, there were lots of polydactyls in the neighborhood were I grew up, but they were all pretty sweet cats, and the ones that were outside were great mousers!

[Freedom]

I usually hear of the extra toes being on the front paws - the "catcher's mitt" type.

That is pretty neat that you have such a special kitty!