Some people run multiple receivers in large/expensive models so that they have what they feel to be redundancy if one receiver fails. Usually they run the ailerons and elevators from one side of the aircraft to one receiver, and the ailerons and elevators to the other side of the aircraft to a second receiver. The other functions are plugged into one or the other of the two receivers. The idea is that if one receiver fails, the other should still work and allow the aircraft to be recovered.

With the Futaba FASST system, you would just link the two receivers in your model to your transmitter. As many FASST receivers as you desire can be linked to a single transmitter.

Some modelers use devices that allow you to connect all the channels to both receivers, and the device uses only one receiver until it fails and then switches the controls to the second receiver.