Very unlikely. Ebay would soon get wise to that and the member would be cut off. (Now there's a horrible thought!). The letters and stars are made up by Ebay, not the bidder.
When you list an item you get the choice to hide or not, the bidders' identity. Simple as that. As a potential buyer, add the item to your watch list and you can soon get an idea which bidder has won, purely through their individual Ebay shorthand IDs. The repetition of those IDs just indicate that their bids have been automatically increased by virtue of their maximum bid already placed. Nothing underhand. Hope this helps.