Honestly that’s a little above my pay grade, if I wanted to answer in good conscience. Personally I look at it like this- God created all things, and science is the study of that creation. So ultimately science will either point to or reveal Him and His hand in our natural world, regardless of what “level” those discoveries are made at (from migratory patterns of great white sharks to cellular biology). In the case of parallel universe or alternate dimensions the question is- How does this effect my personal journey to become a saint in this life? There might be parallel universes, but does it change the things I ought to do cultivate virtue, fight sin and lead a life ordered toward holiness, penance and mortification? I, personally, don’t see that it does.
So what are the “practical” implications of the existence of these things, that’s what I’m driving at. You should check out Fr. Spitzer when you get a chance, he does entire shows around stuff like this. He also has some books out there that might cover these topics, but I couldn’t say for certain.
I’d say don’t sweat it, and work on being holier tomorrow than you were today.