I think the motivation behind the “infinite number of universes” theory has as much to do with providing a way to explain the existence of the universe without a need for a Creator as it does for any scientific purpose.
Since the universe (time / space) requires a conscious observer to come into existence in any form (part of Quantum Theory that has been experimentally tested and confirmed) it begs the question: Whose consciousness are we talking about? Those multiple universes would require the same and the idea might lend a whole new meaning to the phrase “My Father’s house has many mansions”.