I don't know if breeders track extra teeth nor do I know the underlying genetics of extra vs missing teeth but my girl, Tali, had an extra molar on both sides, top and bottom. The vet told me after finding them during the one teeth cleaning Tali ever had; she was about 7 yrs old.
The vet took photos and gave me a copy of them but I've misplaced them now or I'd share them.
Very cool! So she had 46 teeth total then, that's wild!