Find Duplicates doesn't work if you are not logged in. First, it prompts you to log in, but when you do, it redirects to http://www.isfdb.org/cgi-bin/find_dups.cgi , which doesn't exist. It should be redirecting to http://www.isfdb.org/cgi-bin/edit/find_dups.cgi and it should also be passing the record number of the author to the script.
Anonymous
Fixed spelling
Fixed in edit/find_dups.py 1.16 , installed in r2013-58 on 2013-02-10.