Can multiple helicopters be used to lift a heavy load? If the load is heavier than a single helicopter could lift, how possible is to use multiple helicopters for this task?

I have only seen this in some movies. The biggest doubts are


If we attach two ropes to the single point of the load in a V shaped way, a side force will be created pulling the helicopters together into collision.
Even without this, the flight of the two machines probably needs to be very coordinated.


In movies like "Pacific Rim" a whole swarm of helicopters lift a heavy robot. How realistic are these visions?
This video on YouTube apparently shows that it has been done at least once. A rigid beam was used to counter the forces that would draw the two helicopters together.

Screen grab:


I also found this fascinating report (.PDF link) from Piasecki (now part of Boeing Defense, Space &amp; Security) that studied the feasibility of attaching two CH-53D helicopters to each other, including interconnected powerplants and flight controls!