Hi Maria, Thank you for your response. I also placed my question in the FB group. In his answer Peter Bennett also advised multiple sweeps:
“Running the Duplicate File scans is just the beginning. PS uses different methods for identifying duplicates and you need all three Comparison scans to find them all. I don’t have time to go through my complete process but here it is summary
Run Exact file name
Run Any File name
Run File Name and Time Gap exact – don’t reduce sliced as you will get a lot of false postives.
You will need to Mark them manually as PS will not Auto Mark under these settings. Go to drop down menu: Photos/Auto Mark-Similar Photos
Run with exact settings and then start to lower the sliders.
Keep Time Gap at 0 Seconds until you have exhausted all combinations, then run them again with Unlimited time, this will catch duplicates with different or no Capture Dates/Times
Periodically go to Advanced and switch from Bitmaps to Histograms, this will catch duplicates where one of them has been rotated accidentally.
Be patient and I can tell you I typically run about 30-40 scans to get them all. As you begin with the more exact setting, you not find the need to manually check your results, but as you reduce the sliders, false positives will come up and you will need to be more vigilant. Good luck”
PS – Automark Preferences are critical, Number 1 should be Dimensions, Number 2 I use Keywords, but that’s up to you.”
I’ll run the multiple scans next week; and let you know about my results 🙂