Hi Gabriel; Almost all aircraft propellers turn clockwise, from the pilot's point of view, whether they're models or full size. Twins almost always have counter-rotating propellers, one turning each way. This requires two different props.

Another different propellor is the "pusher" type. These are not just regular props installed backwards. They have to turn the same direction, but force air away from the engine, instead of towards it. They're like a mirror image of a regular prop.

I installed a pusher prop backwards, once. It sort of worked, but it wouldn't fly the plane. Installed backwards, the thin trailing edge became the leading edge, so it was still "blowing" in the right direction, but not very efficiently.