Blackbaud NetCommunity does impose rules governing the creation of user ID's when they are created using the New User Registration form, in user administrator and during user import. Users and administrators are restricted from creating user  with duplicate login names. If an administrator or user attempts to create an account with a user ID that is already in the database the person will receive the error "The following error(s) must be corrected before continuing: The Login Name must be unique. Please specify another Login Name."