I think what you said is that you have all these pictures as individual files in folders that are accessed with Finder, just like on the Desktop and other folders, and you can view the files in list view like this
or with icons-- is that correct? You are not working with pictures in a Photos Library, right?
I had pictures from many cameras, film and digital, scanned from slides or prints, or taken off old CDs (remember those?). They were backups of backups, and I had duplicates in double digits.
If you copy pictures from one album to another, the copies will be given names with a number suffix, and you can put them in name order and dump a lot of them on sight. You can try date order to do the same. You do that sort of thing as long as it is simple. But then you need a duplicate finder.
For pictures outside of the Photos Library there are a number of duplicate finders that work well. I mentioned that, for pictures outside of Photos--that are in Finder folders-- I have used Gemini 2 ($20) to deal with duplicate image files. You can have it automatically remove duplicates (a bit scary,) and you can have it display images it thinks are duplicates side by side for your decision. It lists file size, resolution, date, etc, to help you out. Many pictures look the same, but have different metadata or resolution, so this is essential. For me, it was very very tedious and boring, and it took a long time, but it got done. I think.
Another program that I have used for decades (really!) is GraphicConverter ($40). GraphicConverter has a duplicate finder, but I didn't like it as well as Gemini 2. But it does batch renaming and metadata manipulation that's great if you need it.
I hope this is helpful-- sorry about "fixer pro" 😏