Advantage of 2 receivers?
Redundancy...all full scale aircraft are designed with at least one redundant system. On a 757 there are a total of seven hydraulic pumps. And if for some reason both engines and the apu fail...there is a ram air powered pump that allow control of the ailerons and elevator.
Look past just radio interferance when you ask about having a second rx, like the second servo on each surface, batt, switch, wiring, and so on.