An interesting question.

 The "(2011)" is their feedback, and you can find out what items they have been bidding on recently.

I think that the two letters represent a part of their real username. like eBay name = "username" would be "a***m (2011)" for one auction and change for the next auction to say "r***e  (2011)". Would be the same ebay user, but represented differently for individual auctions.

I think that is right - curious to know if that is the case.