Just to go on the other side of the debate, there are a few advantages to having two similar robots. Once both are made, you could use one for practice, and the other for testing new ideas and building. That would involve very close collaboration between the two teams, since one robot would be almost a driver's only thing, and the other could be use to better the overall design of the two robots.

Why make two different robots when you could make one and perfect it? It's like giving two different robots 50% of your genius, or give 2 identical robots 100% of your genius.

While it is true that not all people will be doing things, there will be a lot more work time open since the drivers will be driving the other robot.