What happened to the original Sam Bell?

My wife and I were watching the DVD of Moon the other night. It got to the scene where (spoilers ahead) Sam phones his old home on earth. His daughter picks up — except that now she's a grown woman. Her mom, she informs him, is dead. "Who's that honey?" comes a voice from the kitchen. "Hey Dad, it's someone asking about mom..." Sam hangs up: he can't take any more. "Hey that was Sam Rockwell's voice," says my wife. "That's the original Sam Bell!" Surely not, I tell her. "It was definitely him!" she goes. Luckily, Sam Rockwell and I are best buddies these days — inseparable — and today I had to clarify a couple of things from our interview. So I asked him.

TOM: "Is that your voice coming from the kitchen when Sam Bell phones home?"

SAM: "Yes. That's the original Sam Bell. I don't know who old he is now. He's probably in his fifties. That stuff is all very — its not like the audience has to know that. But I was a pain in the ass about back story. What happened? How many clones are there? Where is the original Sam? How old is he and why did he do this? Duncan would go through it with me very patiently. We went over it a million times.”

TOM: "It makes the clones even more outcast."

SAM: "It makes the original Sam a bit of a dick. He sold his DNA to some company never thinking of the repercussions.”

TOM: "It couldn't be that he'd done his original three-year stint and they took some skin off him without him noticing?"

PAUSE.

SAM: "Yeah, that would work too."