He was killing himself. I think the original stayed there (and dropped into the tank) and the copy was created elsewhere, then the next copy, and the next... But it doesn't really matter.
As I thought of it they were absolutely identical in every way, so it was him regardless of which was the original. That's what I liked about it. He said something about being afraid it was going to be him, but it always was. He had no appreciation for life, even his own, no empathy of what someone else might be going through, even someone he knew as well as himself, while the other men valued the lives of their twins as much as their own.