If you have a command block, cloning a single command block to the location of the clone command block when you clone the block, the command output will  be "No Blocks Cloned". (eg. let's say that a /give @a apple command block is at coordinate: 0, 10, 0,  then you have a command block near it, with the command: /clone 0 10 0 0 10 0 ~~~ [0 10 0 being the coordinate of the command block] when you clone the block, the command output of the cloned command block will be "No Blocks Cloned".) Hope that wasn't too confusing!