I can't help it, I'm a scientist at heart :) Biology teacher at Locke high school, to be specific.

I believe they both are. The main working theory seems to be that these are past lives, or at the very least alternate versions of ourselves that did exist at one point or at some place, so we have lived the lives we remember here on Earth, in Locke or wherever we grew up, and the "other selves" are the homes of those other memories.

[Look who has finally accepted that he really is connected to his "other fellow". It took him a very long time to get to that point.]