@cameron give jdupes a try:
jdupes -rSs ./ > dupes.txt
Will output all duplicates in your current folder, recursively into subfolders, and output to a txt file
Or include the -d flag to let you pick which files to keep, which to delete
Believe me, I've been clearing out hundreds of gigabytes of files for a few years now, most of them are dupes, and jdupes is invaluable.