ah stuff not this myth thing again
no, the berenstein/berenstain/bearenstain/bearanstein bears are not from parallel universes
it's been a long time since i've heard about this (last seen/heard about it on /x/), but somebody ended up pulling up a few good points that rather destroyed the theory
iirc, it had to do with how we remembered the berenstein/berenstain bears being spelled. we end up remembering it either rightly or wrongly, and somebody ends up making it into this big thing
there are covers, i know, that spell the name differently on purpose. if i remember this correctly too, i think there were covers that were spelled different ways in different countries and spelled differently depending on the time period it was from. at some point the books maybe ended up getting shipped in from the other country, and maybe leads to some confusion
in the end i think the berenstein/berenstain/bearenstein/bearenstain bear confusion is just us getting mixed up with how we remember it being spelled from our childhood, especially since so many people say different things about it we end up getting caught up in it too.
if there are parallel universes, a children's book in our own universe isn't going to prove it.