Clones: why haven't more people written about them?

I just finished watching Orphan Black season two. I really enjoyed it. I really like how the show is about clones. The idea feels so fresh. It got me wondering how come clones haven't been done more in books, tv and films? It's hard to come up with an original idea for anything these days because a lot of things have been done to death: vampires, witches, zombies gods and goddesses, fairies, mermaids and so on. But yet somehow clones have not. The only thing I can think that used them is Star Wars Attack of the Clones. It's nice to see something on TV that is brand new and original and not a reboot or based on a bored tired idea.