Same thing happened to me last year - I also checked with the seller as I noticed the email addy was different. In the next 2 days I had another 5 or 6 similar emails, all from different people. I reported them all to ebay. If it is still going on it would appear they can't do anything about it.
I think the problem is that it is too easy to join, so anybody can join under another name any time. Same thing with negative feedback - they just discontinue their negative membership and re-join under another name.