Lordaeron - STATIC dungeon layout (rare spawns, chests)

I've been running SM many many times recently, around 20+, mostly GY and Library, always as leader.

I noticed that the layout of these instances was always the same:
1) I NEVER found Rare mobs in SM GY (and yes, they can spawn, I've seen people with drops from them), even using /target
2) I've always the same types of chests (locked / unlocked) in the same positions, while normally they should be randomised

I know that it's blizzlike for the party / raid leader ID to determine the instance spawns but that should be randomised, it seems to be static here.

Any thouhgts? If some of you can confirm it's a bug, I'm gonna log it in the tracker.