There some sellers that will run up the bids on purpose by logging in on another account and out bidding the high bidder to save on the listing cost of a reserve auction.
I know this to be true because I knew a certain seller that did that because I recognized the id's and have sold to him several times under his "Buyer" id.
I broke him of that when I turned him in after finding out about this. Needless to say he does not sell on there anymore, and he has gripped about it to me in person not knowing I was the one who turned him in. But years ago it would show the buyers id instead of an anonymous id.
Billy