Looking for deduplication tools on Linux there are plenty, see e.g. this wiki page.
Allmost all scripts do either only detection, printing the duplicate file names or removing duplicate files by hardlinking them to a single copy.
With the rise of btrfs there would be another option: creating a CoW (copy-on-write) copy of a file (like
cp reflink=always). I have not found any tool that does this, is anyone aware of tool that does this?