To my mind an infinity of "universes" is pretty much a foregone conclusion, based on the idea that if it happened once for us given the laws of probability it has happened over and over and over and over.

The anthropic principle is not to my mind as persuasive -- inference rather than deduction -- and of course any collision between our universe and another strikes me as mis-definition -- another universe would be in its own dimensions and have no way to influence us -- in other words we are better off to define anything we might react to or collide with as part of our universe.