Well, I raised Bobwhite and Coturnix together with minimal problems. I did raise them since they were very voung (they hatched one week apart). The problem that I did have was the dominant male Bobwhite would peck the coturnix, I had two die from that, but after that it never happened again.
If you are raising them from eggs at the same time, you might be able to integrate them enough so that they might "think" they were the same species, and wouldn't bother each other but that is up to you.
Another note: I kept the bobwhite and the coturnix in the same (decent sized) pen, and they definitely seemed to like to stick with their same species in little groups.