When we got back into the game, it lost our progress and we were back to just before the boss. We also did not have the two yellow items we each got from him. We defeated him a second time expecting the game to just give us two different yellow items. The game somehow remembered that we already killed this boss once even though we did not get any loot or quest progress from the boss. In fact, the game did not even remember we finished the quest, we were put right back to just before him (at the last checkpoint right before getting to him).
Anyway, it would be nice if we could perhaps somehow have a chance at getting our initial two yellow items kill from him. Also, this seems to be some sort of bug that you guys might be interested in.