Put a pusher prop on a normal plane, it will push it backwards.

Full scale twins have all sorts of setups. There are some counter rotating that the descending blade is to the center for safer single engine performance, some like the P-38 mentioned have them going the other way for more maneuverability in a fight, and most have both engines spinning the same way, making the left engine more critical than the right if it were to quit. It all depends on the manufacturer and the engine. Most of the turbines I have flown spin the same way. The counter rotating ones are usually the trainer types and light twins.