Switching BB and adding user to the old BB

I got the BB back from userA at the office, I then gave userA a new BB and assigned him to the new BB.

Then with userB account, I plugged int the old BB from userA and assigned userB to that BB. When everything is done synchronizing, userB now has all of her calendar items in there, but also has all userA calendar items there. As well, it replicated to her windows profile and now it's on her machine also.

Where did I go wrong and how can I fix this situation?