I now have some very nice motor mounts from RoboteerNat to fit our Argos drill motors, and am thinking of going four wheel drive for a pusher robot.

I have this ESC which runs dual motors (hopefully).
https://www.ebay.co.uk/itm/Brushed-E...UAAOSwe2ZbuxLQ

Will I need two ESCs for four wheel drive, splitting the input from the receiver?

Or could I just use the one ESC and split the output in parallel? I'm thinking that would just halve the power going to each motor and not gain anything.