The Saga of Cuckoo is a series of science fiction novels by American writers Frederik Pohl and Jack Williamson. It consists of two novels, Farthest Star and Wall Around a Star. The books feature an interstellar teleporter that leaves the original being behind and sends only a duplicate. When a person is duplicated, the original can just pass out of the machine without a second thought. The copies also can be "edited" at destination. Source: Wikipedia (en)