Results are presented on electron transport in a wide-quantum-well dual-channel velocity modulation transistor, where both front and back gates modulate the resistance through variation of the mobility, whilst maintaining a constant carrier concentration. A mobility modulation ratio of over 100 is achieved at a carrier concentration of 2*10¹¹ cm^-2 by transferring electrons between the two conducting channels which are 100 nm apart. Mobility modulation due to deformation of the wavefunctions is also observed when one of the channels is fully depleted.