Not sure what you mean by the catalog being not corrupted.
All folders had duplicated images within.
Most often with a Name 1.NEF image and a Name 1 2.NEF image, Name 2.NEF plus a Name 2 2.NEF, with the 2 ones being duplicates.
Or a Name 1.NEF and an extra Name 6.NEF and Name 7.NEF image etc. when there were only 5 different images originally, often also an icon with Name 6.XMP etc. as well.
Filtering showed both the Name 1 and Name 1.2 images - and both identical.
Anyway now sorted by deleting all duplicates and renaming and renumbering.
Filter produces one only image now not two identical images.