This is a version of znerp's eBay hide duplicate results script from userscripts.org that works on http://www.ebay.com/sch/. I don't know if it still works on the other urls that are included or even if they still exist.
It has been extended to allow for almost identical descriptions to still count as a match and to report the number of duplicates next to the plus/minus icons.
In addition the user can specify how close the match must be for two items to count as the same.
There was no license specified on the original code so I assume that znerp meant to dedicate his version to the public domain. This version is therefore also dedicated to the public domain.