Uber tristram minions

Hi all
Yesterday i did my first uber tristram on this server and noticed that uber minions continued to spawn even after the death of the respective uber boss (skeletons demons and so on....) . i like it because this makes the quest more challenging.
If I well remember this didn't happen on battle.net. I could clean the entire area. Am I wrong?

 

As far as I know Diablo spawns minions, as long as you kill him, new monsters will not spawn. I may be wrong tho.