Whichever one lags behind, just snip it.. snip it again if it grows, lol. I wouldn't try to separate them unless you are having fun doing it and just for shits and grins etc... if the risk of losing both is okay, go for it, lol.
Maybe, if you germinated using the paper towel method, separating is a more viable option? but that's not the case here.
Allowing both to grow almost always results in one dominating the other. Same reasons you don't want to plant two seeds in one pot -- roots competing with each other is not ideal.