Hey, so this has been bugging me for over a year now. I long ago read in the library a book of short stories. I believe there was one anthology of fantasy short stories and one of scifi, with the same sort of cover and such.
The short story I'm trying to remember was about a young boy who wasn't aware he was a clone, and plays what seems to be some kind of futuristic sport sim game all day long. He wakes up one day with a leg missing, and learns that he was a clone of some rich guy's son, who had an accident playing some kind of sport and lost a leg, and it's revealed the clone is a Never Let Me Go style insurance policy for such an event.
It was a short story, at least 10 years old I think, and I've never been able to find it again. When I first heard of Never Let Me Go, I thought, that reminds me of a short story I read years ago, and it's been bothering me ever since.