I do have a big problem with the WP-Invites Plugin and my WPMU 2.8.3 Installation! The Plugin works fine, but if I activate it, the registration-page doesn’t check wheater the username already exists.
So someone is able to register with the same username. The effect is, that the new user overrides the original one. I need some help! Please!
Here is a discussion about the problem. But there is no solution yet: