Classic F/SF Ideas: Cloning

It should be noted that, despite its technological mystique, cloning is something that occurs regularly in nature - as identical twins.

The real gut-wrenching question at the core of (artificial) cloning is the fact that human clones in science fiction are generally created not to be beings in their own right, but to take the place (or provide spare body parts!) for their primogenitors. In other words, they are textbook examples of treating the subject (an individual) as an object (a thing). That's as bad as it gets, morally speaking.

The Boys From Brazil, Ira Levin
Bug Jack Barron, Norman Spinrad