The other day I was on a borderland at the West “Fire Keep” south gate. right outside was 2 people Fighting-Dueling (1 Ally and 1 Opponent). I attacked. Then I was severally reprimanded by my ally that they were dueling, too which I retorted he has a whole desert up top at their disposal to duel in and to go there and not in front of the doors which caused the keep to be contested by the errant projectiles from the opponent. That said it is about the location you pick to duel in on whether or not the duel will be interrupted by another player. PICK WISELY AND PLAYERS WILL LEAVE YOU ALONE… PICK POORLY AND EXPECT OTHERS TO CRASH YOUR PARTY.