any known reasons why the prog would overlook duplicates? These were exactly identical, in name, size & contents. Stored on USB stick, external HD, internal HD.
Others, in exactly the same category (and even folder) were 'discovered'.
Got a similar problem while extracting an archive file to an external USB drive. Seems that writing to a (too slow ?) USB drive can change the creation time stamp of a file. Don't know why that is.