Instance pre-determined spawns & loot - NOT randomized

This is for LORDAERON

I've noticed that rare spawns and boss loot does NOT seem to be fully randomized.
Instead it seems to be fully pre-determined by whoever enters the instance first (or who's leader, I don't know).

1) I had run many (10-20) SM GY runs on a character, I've never seen a rare boss, not even once.

2) I've done 3xGY, 3xLib, 2xArmory in a party where I was leader and entering instance first in all cases, drops were:
3x Bloodmage Mantle from GY
3x Robe of Doan from Library
2x Ravager from Armory

3) I always see the same types of chests (locked / unlocked) in the same locations, while on retail (or other WotLK realms) these would be randomized at each instance reset.

The chance of the above loots to appear in exactly that combination is astronomically low, if my math skills aren't too dusty
(1/2)^3 * (1/4)^5 = 0.00012207031
(about 1 in 10.000)

This is not normal, right?
I'll log a bug in the tracker if someone else confirms this