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.