fdupes

delete duplicate files without conformation

fdupes -r /path/to/folder

To manually confirm deletion of duplicated files

fdupes -r -d /path/to/folder

To automatically delete all copies but the first of each duplicated file

(be warned, this actually deletes files, as requested)

fdupes -r -f . | grep -v '^$' | xargs rm -v

I'd recommend to manually check files before deletion

1. write duplicates to text-file

fdupes -rf . | grep -v '^$' > files 

2. then manually check the files to delete and remove files that should not be deleted from file 3. remove all files that occour in the text-file with:

xargs -a files rm -v