Oh you mean files already on your harddrive instead of files you need to download.
I don't know any special programs for it, but here's a simple method. Go to Find Files or Folders and type in the file extension, like *.jpg. This will give you a list of all the image files you have. Now sort them according to size. Many files will be the same size, look through them! and delete the extraneous ones.
However, if you have like 70,000 files, then this process would be very tedious.