So, my idea would be(sorry for my english in advance):
1. case :When someone place a control ward somewhere, then the enemy team would put a normal ward close to the control ward instead of disabling it, kinda "hacks" it. What I mean under that? Seemingly the other team would have vision of the area that the ward provides, but in reality it wouldn't show anything to them what's really there, not even the control ward.
2. case: You put a ward in the bush, then the enemy put a control ward there. For 3 sec it would disable the ward (like now) then after the 3 sec it would show the false vision explained before.
Feel free to share, if you think it would be a bad idea down below