This is a neat utility to scan folders and find duplicate files (based on contents or names) or similar files. You can replace one set of files with a hard link so that it only takes up one file worth of space. You can have it delete duplicate files automatically. You can search based on filename, date, size, or full contents.
https://www.majorgeeks.com/files/details/clonespy.html

Keywords: Find, delete, duplicate, identical, same, equal, folders, files, compare, comparison