Photos folder list does not have a "Duplicates" folder on my iMac.
Photos folder list does not have a "Duplicates" folder on my older iMac running Version 16.6 (17615.3.12.11.3, 17615) I have about 5,000 photos in my library and numerous albums with known duplicates. I have yet to see the "Duplicates" folder name.
Earlier Mac models