fdupes does a great job if it's just one filesystem. Can delete the dupes or just hard-link which is sometimes more useful.
But before I bothered to look and see that someone had already solved my problem, I wrote a script (in bash) that would list all the md5sums and paths in two columns, sort by md5 and delete all but the first of each. It wouldn't be hard to do this for 11 filesystems, just extend it a bit so that you include the drive it came from, the date perhaps, apply whatever logic you want to the lists and generate 11 scripts as output that get run back on the original machines.