Most of the time the two groups can just ignore each other. That's fine. The violence came from the fact that the offensively violent ideology (the "Destroy all other ethnic groups" one, to be clear) attacked people my ideology sees as being in our in-group (approximately everyone who's not trying commit violence upon other people at random), justifying defensive violence in response.
If half the class thinks blue eyes are superior, and the other half think brown eyes are superior, but no one's attacking each other and no one's oppressing each other, then there's no conflict. It's still not going to useful to sit around and argue philosophy.