Binary package “duperemove” in ubuntu kinetic

extent-based deduplicator for file systems

 Duperemove is a tool for finding duplicated extents and submitting them for
 deduplication. When given a list of files it will hash their contents on a
 block by block basis and compare those hashes to each other, finding and
 categorizing extents that match each other.
 On BTRFS and, experimentally, XFS, it can then reflink such extents in a
 race-free way. Unlike hardlink-based solutions, affected files appear
 independent in any way other than reduced disk space used.