HALLOWED GROUNDS - Nadijeh Achievement

So, my friends and I were trying to do the achievement for Hallowed Grounds where you find the right Nadijeh clone without killing them all.We had not killed any yet and then suddenly Rytlock, Kasmeer and Canach killed one and we lost the achievement. I know they are intended to attack so they are actually a really good help on story missions, etc. But they just messed up our attempt at the achievement. If they could be disabled or unable to do damage during the clone section would be nice.