Your experience meeting the same person in two different worlds is very fascinating. I am curious as to how it happened to you? Did you cross over by accident or did you have some kind of desire for it to happen? I ask because the mind is capable of shifting to a parallel world at will through desire, visualization, and daydreams. In the book "Parallel Universes of Self" the author Frederick E Dodson states that you can shift to parallel worlds at will and you can do so based on what you desire in life. But after reading the author's book I can assume that you most likely can't go back. I would not say that it is completely impossible, but it is probably highly improbable. You mention connections to both sides or parallel worlds. You may be on to something. I could never understand the parallel world theory based on the mind only making the trip. How can I only be self-aware in this dimension but not in all of the others? I think all the other parallel worlds exist in a virtual state and don't manifest or become real until you enter it. This is actually a quantum mechanics principle. However, as I mentioned it might not be completely impossible to return if you use some of the techniques in Dodson's book. An alternate or more simple way of learning them can be obtained from the video "The Secret". This video is where I was first exposed to all of this, achieving what you desire, "attractor factor principles, and ultimately wanting to move into a parallel world.