Real coaxial helicopters do exist !

Coaxial means two groups of counter rotating blades above each other.
This is the a Russian Kamov attack helicopter. Ka-50. (Also known as Werewolf or Black Shark)

Because it has no tail rotor, the machine is less vulnerable and its manoeuvrability is better.

Ascent and descent is controlled by the speed of the blades. So in order to take off the blades start rotating faster and faster.

With a traditional helicopter the speed of the blades is fixed. By turning the blades to a different angle, they get more "bite" in the air and the helicopter lifts off.

Another Russian helicopter with 2 times 3 blades.

The real Dauphin however, has traditional main rotor blades and therefore needs a tail rotor.