Source:  eDirectory or NDS

Explanation:  This error notifies you that an attempt was made to do one of the following:

For example, you assign Bob a security clearance of Novell for logging in to the partition. So you give all users a level of the security clearance of Novell. Dave comes along and you want to assign Dave an additional security clearance of SSL, so you assign Dave a security of SSL and Novell forgetting that Dave already has the Novell security clearance. This error would be returned because Dave already has a security clearance of Novell.