Can I operate more than one motorized wheel from one motor control unit?

Theoretically you can if the motors are sensorless, and the speed controller as well, but in reality not, because most of the motor are sensored today, and also most of the controller can output a limited amount of current, and sure not enough to power even 2 low power motor. It might work with no load, but sure the controller will broke after you sit on the bike. There are out there some really powerfull controller, but the cost are not worth the risk. You can use one throttle with 2 controller, this is doable and done in the past, but you have to build yourself the split cable for both the controller. You also have to think about the battery, which might not be able to output current for 2 motor, to be safe you should use high quality cell, with 5/10C of discarge rate, or compensate with a lot of parallel batteries, which means 14Ah 36v batteries as bare minimum, better 48V 14Ah. This number are just said to be said, without any calculation since here we have many many variables.