qlsdup
GUI based lightweight duplicate file finder / remover.
... for large file sets with few differences: basic set of duplicate candidates is determined by file size, then candidates are compared byte-wise. So for files which don't start to differ by growing at the tail it reduces read operations greatly compared to hash-based comparision (i.e. test case: 40GB of files, 16GB RAM, many differences: initial compare (uncached by OS) around 300sec, subsequent compare (relevant file parts cached by OS) ca. 2sec)
Note: this program is not related to lsdup