Roy wondered what would happen if the second target for the device weren't even a person. Would it work? Would it do anything? Would it do something weird and unpredictable? Deep down, Roy was a curious experimenter (just like his alternate doppelganger from the other reality). He looked for an inanimate object for the second target.
There were a few things around that Roy may have picked from. There was some dirty, plastic kids toy that was sitting in the display near the counter. He also thought about picking something in the back room. There was a dirt sink, or maybe a mop that was sitting in the corner. He also had seen a dollar bill in the cash register before and wondered what would happen there.
He had already made up his mind as he decided on the object as he selected it and then hit the second button...