I believe the episode is titled: "Eat Me". Anyway, something that I just can't get out of my mind is how do we know the Chiana and D'argo that survived are the real ones and not the doubles?
That's the fun part: we don't! As I recall, D'argo brings up the question at the end of the episode, but Chiana gets too disturbed and tells him not to think about it. Of course, Kaarvok said that his machine split the host into two identical halves like cell division, meaning that neither John twin on Moya by the end is the "original", but he could have been lying. And even if he was right, there's still the fact that Chiana watched a perfectly valid and identical version of herself get killed and ran away instead of helping. That's brutal!
It's always a cliché in sci fi TV episodes about cloning to conveniently get rid of the clones by the end or find some other way to go back to "normal"--The Almost People from the new Doctor Who is a bad example of this. To me, Eat Me is one of the best Farscape episodes not just for being the scariest, but for also taking a sledgehammer to those clichés.
When I dreamed of Broadway, I never pictured the elk antlers.