Four-prop aircraft don't contra-rotate, because the props are too small to create enough torque to affect the stability of a 70-ton aircraft.
Except for Avro Shackleton's, which had a pair of contra-rotating props on each nacelle, and the Fairey Gannet, which had a pair of contra-rotating props, because it had two engines, enabling it to shut down one engine and loiter for hours at a time. Fantastic aircraft, like the Harrier, should never have been scrapped.
Those huge props on the Osprey would turn the thing in circles on its axis as soon as it started up, because of the torque, and there was at least one hekilopiter, like the little r/c ones, with a pair of contra-rotating rotors, one above the other, without a tail rotor, to avoid torque-induced spin.
The Shackleton had Griffon engines instead of Merlins, which were slower revving, using conventional propellers would have needed an increase in propeller diameter to absorb the increased power and torque of the Griffons, which was not possible due to limitations in undercarriage length and engine nacelle positioning of the Lincoln wing; the contra-rotating propellers gave greater blade area within the same overall propeller diameter.
Clever design, that.
I love those Osprey's but sadly never seen one flying, they don't come over my way, especially now Lyneham's closed.
Pity, cool plane.