ParDRe
Parallel tool to remove duplicate DNA reads
...It is faster than multithreaded counterparts (end of 2015) for the same number of cores and, thanks to the message-passing technology, it can be executed on clusters.
There also exists a MapReduce counterpart of ParDRe, called MarDRe (see the link above).
UPDATE: From version 2.0.5 ParDRe also provides support to remove only optical duplicates (and leave biologically interesting duplicates) as well as to work with compressed input/output with .gz format.