The twin rotors spin in opposite direction to help with stability. They kinda of counteract each other.
There is another reason to have twin counter-rotating rotors.
In a single rotor helicopter, one side of the rotor is flying into the direction of flight. The other side of the rotor is flying away from the direction of flight. This means you get a whole lot of lift from one side of the rotor and almost none from the other side. The faster you go, the more pronounced the effect becomes until parts start breaking. This is one of the big reasons helos are so speed limited.
With the twin counter-rotating system, each side of the aircraft has a rotor flying into the direction of travel, canceling out the other side of the rotor flying against the direction of travel.
Jim Snover
so the only helicopter in the world faster than my GT is this?
weak sauce....