[starscream]

Dual ESC's running a BL motor each seems very different than a single ESC
running Dual brushed motors. Unless the ESC's are sync'd somehow, a dual motor setup will never be as efficient as a single motor setup.
A dual brushless setup would provide a lot of torque but is impractical for most applications. The vehicles drive train is already heavily taxed by a single BL motor setup. I would imagine you would find your drive train's weakest links pretty quickly with a dual BL motor setup.