Error Failed to save user : A database login with the same name already exists.
When modifying a user or add/remove rights to a database.
Please tell me if you see this problem and what the solution could be.
We cannot reproduce this issue. Although, we are glad to assist. If you wish, you could write a private message to @staff with your server login credentials, referencing this ticket, and one of us will login to your server to have a closer look.