You can try with fdupes.
fdupes is a program written by Adrian Lopez to scan directories for duplicate files, with options to list, delete or replace the files with hardlinks pointing to the duplicate. It first compares file sizes and MD5 signatures, and then performs a byte-by-byte check for verification.
fdupes is written in C and is released under the MIT License.
1) To install fdupes, open a terminal and type:
sudo apt-get install fdupes
2) For a basic use.. to search recursively for duplicates files you can do the following:
fdupes -r ~/Videos/ > ~/Desktop/duplicates.txt
With this command fdupes will serch recursively in the folder "Videos" in your home Directory and will save the result in the "duplicates.txt" file in your Desktop.
In this example fdupes found that:
are duplicate files.
are duplicate too.
NOTE: (The results will have all duplicates separated in groups of the same file, with groups separated by a blank line.)
So , you can view the "duplicates.txt" file to analize what files are duplicates.
3) Fdupes also has an option to prompt the user to delete de duplicate files.
With the -rd option fdupes will search and prompt if there are duplicates files, what file do you want to preserve. then will be delete the other ones.
user@Ubuntu:~$ fdupes -rd ~/Videos
Set 1 of 3, preserve files [1 - 2, all]:
For more information you can view the man pages
I hope it helps!.