The question is - how do you connect two ESCs to a RX? Do you have to (is it OK to) cut the red wire on one of the ESCs?

I built a model of a ferry boat. It hastwo motors each with its own battery and its own speed controller.One will be plugged in to slot 3 and my RX and one to slot 4. The idea is that the motos will run independently --at 12:00 on the throttle both will run forward and at 6:00 both will run in reverse. At 3:00 one will run forward and one will run in reverse, etc. But if I plug both ESCs to the RX, won't I give the RX two doses of power? Should I cut the red wire on one of the ESC's?

You are correct, don't want competing power sources. But consider doing it in a way without cutting the wire in case of wanting to use the ESC normally in the future. One way is to bend the small tab and pull one connector out and shrink wrap it or something secure to insulate. Another is use a short servo extension and cut that up, again being careful to not leave any wiring to touch later.

Thanks, good advice. I'll put those ideas to work tomorrow am!