Greetings.
I've just done Crown Chemical boss and for some reason the boss respawned after we killed him. This happened about 5 times in a row, the cause could be anything from the following;
neither one of us were using the perfume/cologne buff
had a hunter f:d by the end and md pet
not using a healer
not quite sure how it happened however i'll look into it more tomorrow to keep you updated.