If you are managing a large amount of photos, videos or other media, you soon end up with multiple copies of files in distant directories. The tool you need to clean up this mess is a duplicate file finder. On Ubuntu, a good tool to do this job is FSLint.
Installation is easy:
$ sudo apt-get install fslint
After installing, open FSLint, add the root directory of your files and click on Find. FSLint churns through your files and find the duplicate files.
Tried with: FSLint 2.42 and Ubuntu 12.04 LTS