If you notice that they are spinning around alot together than you problably have a pair. If the dominant just keeps the other under cover alot they are probably two males, dominant and sub-dominant. If you notice that they seem to lock lips and try to push each other around than they were probably both dominant at one time. Either way, Ps. Crabro are very aggressive. If you want to keep more than one alive than you need to have about 6 of them. More fish will spread out aggression and keep the dominant male from killing the other. Adding more will also increase your chances of females anyways. What size tank is it? Are the Ps. Crabro and the Auratus the only three in your tank? If so the situation may be critical; mbuna are much better off over-crowded than under-populated, especially the more aggressive ones.