The Agent Smith problem. Right now if an entity in meatspace wants to copy itself it has to breed, and for anything complex the copies are not the same and have to go through a growing process. With copy teleportation it's not really any different than Ctrl+C/Ctrl+V on your computer. As long as you have the energy you can build entire armies of yourself. There many be plenty of good scenarios for this to happen but I can think of far more downsides.