The seller of this coin:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...em=190027525555
has two others for sale, all extremely rare. What is especially interesting is that these same three coins, at least according to the photos, were just sold a few days ago. The 1751 double ducat brought $440 in a 'private' auction. (The seller also has hidden feedback, very suspicious for high-grade rare coins.) The $440 is less than 5 percent of its true value.
This has all the earmarks of a Ukrainian operation, where an old eBay account is hijacked and coins not owned by the seller are sold to unsuspecting buyers. The seller's ID is similar to others who have pulled this charade. Some of the terms have been literally translated from the Russian into English and have become meaningless in the process. In particular one of the three coins has "a stamp field," probably a mistranslation of "well-struck." This indicates that the sellers (who use 'gramme' rather than 'gram' as would normally be used in English) really know nothing about the coins they claim to own.
RWJ