The great thing in tor is that boss drops are actually smart. It knows what classes are playing and drops gear for them so there wont be IA loot if there is no IA in group.
There probably is just 1-2 items per class on the boss loot tables so if you get bad luck with same class getting the drops it might look that the same item is dropping all the time
I've had class inappropriate loot drop several times, so that shook my confidence in this theory.
Granted this was at a lower level when my friend and I were duoing BT as my Sniper with Kaliyo, and his SI with the tank dude.
It was all Powertech drops.
Couple other cases, but since I also have a PT and we got all IA drops on that run, we had to laugh.