Any kind of dueling on a battle server at the round end phase ( i.e the last few survivors ) is just stupid, whether or not it's against a team mate or one of the enemies, it's retarded.
Why? well even dueling against your own team mate when it's 12 v 1, we have all seen that one guy kill them all, it happens quite often, so whilst he could have killed all your team mates you two were too busy slapping cocks together to help them kill the mad man. Or the most annoying one is when it's like 8 v 1 and they then all proceed to duel the 1 guy and all die, losing your multiplier. Yeah the duel server is that way bundle of stickss, we play the battle server because we want to play battle, not duel.
I have had team mates intentionally getting in my way trying to make me hit them instead of the enemy because they're trying to force me to let the duel happen, that's beyond retarded but that's another topic.
But basically the rules state no team wounding or team killing whatsoever, you do it at your own risk regardless of the situation.