I am using DNN 3.3.3
I register a user "AAA" in the first portal, then in the second portal,
when I try to register the same user name with different  password, it complaints "User already exists", should it allow same user name for different portal?
the next problem is even worse, it allows me to register the same user in the second portal if I use the same password as the one in the first portal, after this, DNN mess up, two portals are sharing the same user name, whenever I change the password/profile in one portal, the same user in the second portal is changed automatilly!
then, I try to delete that user in the first portal, whenever I try to login to second portal using that user name, I got error "

Server Error in '/DNN' Application./

Object reference not set to an instance of an object."

after all of these, I have to goto the second portal to delete that user to fix the problem.