It is a good concept. Altuogh at this point I seen this "past me" ideas multiple times, th "blue zone" is very unique and creative. However I would not despawn the past version. This was a deafult by every other similair genre, and I was really missing it here. Maybe it was intentional from you part since because of this I felt some urge to be quick, but it also caused me to just stand in one place for a long time, so that my future self will have time to arrive there in time.
But good job on the game.