Alternative:
For many years now I have used a program called AllDup Portable from AllDup.de. It’s free, supports many languages, very fast even with many thousands of files. You can set what to check for (I have it ignore name and date, check if same size and content (only calculates checksum if two files are same size). It then groups all the duplicates in a list and you can quickly preview every match to make sure it’s a duplicate, and decide which to keep. So many options. I think it has a steep learning curve but also think they have managed that well with all the flexibility. My advice: download it, then set copy files into some new folders, make sure you have duplicates, then run the program and play with it to understand how it works without the potential for losing files you still want. Truly an amazing program!