If you created the auction as a "Private" auction then all bidders will show up like that. It's an option that you as the seller can choose when listing the item.
Usually only smut peddlers and antiquities dealers or those selling expensive items that dont want their customers poached use it.
Often times in high price auctions other sellers will try emailing the bidders to offer them a better price. Using a private auction would stop that. The negative to that posistive is that you cant tell who is bidding and that seller could be using their friend to jack up the price of the item and you'd never know. So that is the reason not everyone uses them on high ticket items. It sorta scares bidders away when they cant see who is bidding against them.