What is the helicopter with two rotors called?

One of them is called Boeing CH-47 Chinook, a large transport helicopter in service with many airforces .The Chinook is a tandem, meaning the rotors are in front of one another.

There are also others - a Kamov- Ka 50, a Kaman Kamax (or a Husky)

and even the V-22 Osprey.

There are tandem and intermeshed rotors (angled into each other) and coaxial rotors (one on top of the other)

Look up the examples above for pictures of each type.