Unless its with lance couching, theres no way to kill each other without ranged fire: Tried very hard with a friend on native duel, both with same class and weapon, release attack at SAME instant, but it wont accept it, ONE always hits first....suck really.
ALSO I was really excited when I read the topic name, though someone had figured out how to kill 2 ppl with a single attack, THAT would be epic. Closest Ive seen is a crossbow bolt penetrate the shield of a player in front of me, miss him and headshot ME, 10m behind him....