After using the PIU there are duplicate cardholders
Windows Server 2003
Windows Server 2008
A unique alias must be specified with the transform or duplicate records will be created
Each alias must be unique. Information that is updated for a personnel object will be triggered off the alias. If the alias already exists in the database, then just the new information is added. If the aliases are not unique, a new record will be created. (See “Saving a Configuration and Importing Data into CyberStation.”) To verify this, when previewing your data, make sure that every alias name under the "Alias" column is unique before importing.
See Lessons Learned Article #13732 for more information