The Berenstein Bears. Remember them?
Looks like someone went back and time and changed it to The Berenstain Bears. Ain’t life interesting.
-stein fits the rules of spelling we absorb when we’re young and not -stain, so our memory folded it in wrong. It’s cool because subjectively, I remember -stein. Amazing stuff that
Of course what doesn’t help is EVERYBODY spelled their names wrong, littering history with -stein endings locked inside of old books.