Sorting old photo backups

The time has finally come to sort out my old folders of photos - it’s the stuff from the years of digital cameras prior to iPhone which as it happens was when the kids were babies so there’s a lot of it.

In the past I used to run big additional HDDs in desktop PCs and latterly on a NAS so I’ve got loads of folders with names like “photos backup” and “photos form old laptop”. Some folders have been given names that seemed sensible at the time, some are as they came of SD cards. So lots of nested folders. There’s also bound to be loads of duplicates both where the same photos been taken multiple times, and where my “archiving” has just been “save a copy of everything to a bigger disc”

Basically it’s a hot mess.

I’ve pulled everything down from my NAS and I’ve got around 500gig of photos on a fast external SSD

I think what I want to do is run something to pull everything out of the existing file structure into a single folder or folders by year or something like that, then I’d like to de-dupe everything based on meta data. I wouldn’t be surprised to have several copies of the same photo all taken at precisely the same time. Should be easy enough right?

Once I’ve got a shrunk down number of photos I’ll probably put them on iPhoto

So, can anyone point me in the direction of software and an idiots guide?

Im on a new Mac mini but could fire up an old windows laptop if necessary. Mac is the most powerful machine in the house tho

Any help gratefully received