Peacemaker

Peacemaker (1990) is a science fiction, action directed by Kevin Tenney rated 5.4/10.

Two aliens arrive on Earth trying to kill each other. This is not easy, since they seem to be able to regenerate lost body parts and survive bullet wounds. Both of them happen to meet a young pathologist Dori Caisson, and each alien tells her that he is a peacemaker (an intergalactic cop) and that the other one is a bad guy. Whom can she trust?