What forces the worlds to be same in order to interact? You could also have merely adjacent worlds where the "collisions angle" could compensate for small differences. It is just a little harder to imagine how worlds of unrelated state would interact. Maybe dark energy is the sum total of gravity from other worlds?

It's also that two worlds won't long stay singular, but branch all the time into subworlds. The probability of some of the pairwise worlds being close enough is higher.

edit: Also there are settings where splitting doesn't mean lack of structure. For example in the mirror experiements the two paths will systematically intersect and this is a pretty stable result of the mirror positionings.