dupehasher
Shell script for managing duplicate image files in a directory.
... (post-deletion) files in a chronologically-sequential manner; or according to the md5sum or sha256 sum of every file.
File extensions (.jpg for example) are preserved, and there is a user option to ensure that the extension is correct (for example, a .jpg file is indeed a jpeg and not, for example, a png).
Finally, an interactive mode exists for users who are not comfortable with the command line.