Azmael doesn't recognise the Doctor as another Time Lord. Usually Time Lords recognise each other despite having regenerated
This is what I was coming in here to say. The Doctor always says that he would be able to sense another Time Lord, so I would have thought all Time Lords could do the same
As examples, both the War Chief (The War Games) and Runcible (The Deadly Assassin) recognise the Doctor, even though they can't have seen his current version before.