Ok this is getting annoying you need to think of making system were we can identify friends from foe...

It is impossible to tell difference who is who... We are not computers to remember the names of all our allies and you have to get up close to find what their name is and you dont have time for that if its foe by time you tryed to look for name your dead... So you kill first and ask questions later this can cause much confusion between allies and friends and get tensions high...

You need some sort of diplomacy implemented and people within tribe should see name tags clearly and you should be able to make NAP with tribes and see their nametags in different colour to avoid such pk...