Each organisation will have it's own process for managing duplicates in iMIS. Both for during data entry and on a regular basis using the duplicate merge manager. But how long ago did you last review this process? And check that those responsible are running it correctly?

Might be worth an hour doing your own dup check. Change the dup check formula to something stronger, or something weaker. Then run it again. You may get some surprising results.

Steps to complete:

TBC