http://biggerluke.wikidot.com/canon-luke-hypothesis
>R2-D2 Cloned Luke
>With the release of the prequels, it was discovered that R2-D2 is heavily woven into the backstory of Star Wars, and therefore must possess a foresight that most other characters lack. It can also be assumed that R2-D2 must have assimilated some knowledge of cloning throughout his adventures, having been smack dab in the middle of the Clone Wars for quite some time after all. It should also be noted that R2-D2 did not have his memory wiped, unlike C3P0, and unlike Obi-Wan, being a machine, R2 would see things in a strictly pragmatic fashion. not shying away from cloning if it suited a purpose.
>R2-D2 must therefore be aware of how potentially integral Luke Skywalker is to saving the galaxy from the Empire. It is possible that, whilst Luke was away - perhaps shortly before running away to find Obi-Wan Kenobi - R2 managed to clone Luke in some fashion, perhaps as a backup in case Regular Luke died, and randomly shuffles them around through a complex system of teleporters and cryosleep pods. Perhaps Luke's conciousness is transferred back and forth between bodies? Perhaps he notices no difference in between transferences, not even aware he is being shuffled between different bodies.