It has been reported that /clone also clones blocks even if there are no changes to be made (You clone a cube to the location of a simulair cube and it still replaces everything, for example). BUT now I noticed that when doing so by with redstone, repeaters and all other blocks that need another block in the proximity will be dropped as Items on the ground. Very annoying of course.

To be clear, it's the old redstone that is being dropped (not the ones that are getting cloned) since you still see redstone placed where it should be.

Screenshots and more explanation:
http://imgur.com/a/CRxF6