There was something that was said in Wakanda that I think means he has had the dreams as well. Something along the lines of "Even if things are different here...."
However, just enough has changed that anything the other Thanos did wouldn't apply. We've clipped his wings. And we have his gauntlet.
Also, if the Prime Universe's Thanos literally poured over into this universe? Two powerful beings in one universe, running the risk of them meeting face to face, would create a dimensional paradox that could destabilize everything.