The aircraft came down at the Potrerillos de Mendoza dam in western Argentina, officials said.
MTV said the helicopter was flying to a shooting location for the show The Challenge.
Neither of those killed was a cast or film crew member, the US channel said, and no-one else was on board.
Divers were having difficulty finding the bodies, the security minister for Mendoza province, Gianni Vernier, told Telam news agency.
The wreckage lies at a depth of 60m (200ft).
It was the second fatal crash of a helicopter involved in a reality TV show this year in Argentina.
In March, three French sports personalities were among 10 killed when two helicopters collided in north-western Rioja province.
Yachtswoman Florence Arthaud, Olympic swimmer Camille Muffat and Olympic boxer Alexis Vastine died with five other French nationals and their two Argentine pilots.
The helicopters were involved in the filming of the TV survival show Dropped.
A helicopter which was being used for filming an MTV reality show has crashed into a reservoir in Argentina killing the pilot and a technician.