I know it's terribly clichéd to put two identical characters together so even the audience doesn't know who the real one is, but the opportunity presented itself, and it just seemed the thing to do. I mean, whenever you're confronted with imposters, twins, or alternate versions of a character, aren't you required to have them enter into a scuffle at some point?
In Family Guy, Peter defeats his evil robotic twin (or did he?). In every remake of The Parent Trap, the twins (or computer generated twins) switch places to fool their parents. In Star Trek: The Next Generation, how many times did Lore pretend to be Data? And what about that time Thomas Riker pretended to be William Riker? And in Sliders, remember when the Professor got into a fight with his alternate, one of them slid leaving the other behind, and we never did find out which one was which?
But at least I'm aware of the cliché, and allowed Proto Man to cut through all that unnecessary plot and get straight to the confusion, right?