ShipScript has been an eBay Community volunteer since 2003, specializing in HTML, CSS, Scripts, Photos, Active Content, Technical Solutions, and online Seller Tools.
People have asked me for a Duplicate Listing Scanner, similar to my scanner for eBay Photo Size compliance, and I had declined in the past because it is too complex a problem. But I was again encouraged to create one, so here is the beginning of one.
http://www.isdntek.com/ebaytools/DuplicateListings.htm
It first looks for duplicate titles, but a duplicate title is not enough to violate eBay policy.
So it further looks at the duplicate fixed price guidelines and the duplicate auction guidelines, and tries to take a measure of price and auction type to report the probability of being a duplicate listing, and then displays the results using color coding. Because there are more parameters to consider, like photo, item specifics, condition, and subtitle, this scanner is not conclusive.
The scanner simply finds items with duplicate titles so that you can decide for yourself.
If someone is circumventing duplicate policy by adding a character to the title, this tool will not detect it.
If you think you may have duplicate items, I would love to hear from you to help improve the tool.
Your site is phenomenal! This was my first visit to it and your tools are simply incredible! Thank you! 
