CSV Import - Option Warn with report on duplicate uid or Fail with report on duplicate uid
On import, a person would be able to choose Warn on duplicate entry, to let the import proceed with warnings on records which failed because of an already existing uid. At the completion of the import they would be able to see a list or export the list as a csv of records not imported in order to address the ldap entry if it requires altering.
If the user chose to Fail on duplicate entry, they would have access to a report of those records not imported, or, it would explicitly show for which record the import failed. This way the user would be able to make note of the problem record, continue the import, until the next fail repeat.
There is also room for a more advanced Interactive option to allow the user choose what to do with the record in conflict.