I came in far too late to join the discussion below, and it's not easy to branch off into a different mode of reasoning.
What physical attributes would both Univeres's share?
Or prehaps what would be the biggest difference.

An explanation of the fundamentals could help give one a deeper insight into whether there is a Multi Universe state at all.

"You will never find a real Human being - Even in a mirror." ....Mike Kremer.