For brushless..
Connect the two ESCs with a Y-connector, plug that into the receiver channel.
Some folks disconnect one of the red wires in the cable from the ESC to the Y-connector.
The best way to do this is add a short... 3 inch or so.. ordinary extension harness with the red wire cut, instead of cutting the red wire in the original harness.
You don't have to repair the original harness when you need to use it somewhere else.
For brushed.... A single ESC can be used, if the power needed doesn't exceed its rating.