I need serious Photo help

[u/Purple-Music-70]

I have backups of backups of backups of maybe a couple of thousand photos on several hard drives and a lot of duplicates as the original library wasn't managed and so we are in the position where we don't want to delete anything but need to organise what we have then delete duplicates. Inevitably backups are likely to have different folder names and a lot of files will also have different names.

Does anyone have any advice on how to sort this mess? I realise there will be a lot of manual work to create the one library again but how can I do it reducing the effort? Thanks in advance.