Scary, isn't it. A typical 120v. receptacle is fed from a single breaker back at the panel so you still have a 15 or 20 amp limit depending on the breaker size. It is possible to separate the two outlets of a duplex receptacle and is often done with a living room outlet so a table lamp can be put on a switched circuit. Virtually never is a duplex receptacle fed from 2 separate breakers (and is probably a code issue). In the extreme rare instance it might be, it is highly possible that the phasing is different for each outlet and a direct short would occur if both of those male prong sets are interconnected.