It's a completely broken mess and my guess is that your inflated pet damage numbers on Blackrock are due to your gear not updating your pet stats properly after unequipping. In contrast to this, stats update perfectly on Icecrown, which is why you're seeing the proper damage values there.
Forgot to mention that I was using glyph of imp on both servers.
A 20% increase in damage will not turn 500 into 1000. Your pet's stats were clearly bugged from unequipping gear as I've already shown. Also, we can clearly see that your naked test has a difference of 500 SP between the servers, which invalidates it even further.
not sure if you saw the last picture and why you are acting like there's nothing wrong, I wouldn't have gone to make tests in first place if I didn't feel like my imp is doing a lot less dmg then what he should, how come a 5k warlock's imp crit for 4k dmg while in icecrown 6k's crit max is 2k (same glyph/talents/self buff).
And I tried both pvp/pve gear while resummoning the imp each time.
not sure if you saw the last picture and why you are acting like there's nothing wrong, I wouldn't have gone to make tests in first place if I didn't feel like my imp is doing a lot less dmg then what he should, how come a 5k warlock's imp crit for 4k dmg while in icecrown 6k's crit max is 2k (same glyph/talents/self buff).
And I tried both pvp/pve gear while resummoning the imp each time.
I'm not saying there is no possibility of something being wrong, I'm simply saying you have 0 evidence because all of your "tests" were made on a server where pet stats are clearly bugged.