Instead of creating such a hybridized two-unit set with one prime mover unit and one brake resistor unit, which would have to be heavily ballasted, you might as well just provide both units with prime movers AND massive dynamic brake capacity ... especially considering that there is not only a limit on tractive effort dictated by locomotive weight and adhesion control systems but also a limit on braking effort. That limit is also based primarily on locomotive weight.
This has of course been done - perhaps the earliest example I can think of off the top of my head was the Fairbanks-Morse H24-66 Train Master, advertised with a 2400 HP for traction rating but with a dynamic brake capacity of 3600 HP. If you find a picture of one of these, you'll see that the dynamic brake assembly really doesn't take up all that much room.
-Will Davis
WILL DAVIS
Moderator- Steam Locomotives forum
http://www.railroadlocomotives.blogspot.com