If I understand you correctly, it sounds like the usual proxy bidding, - when someone places a bid early on and if by the end of the auction no one has surpassed it, that early bid will appear as the 'last' bid. The reason for this is because it was the highest bid. The highest bid always wins, no matter when it was placed.
When you are looking at the Bid history of an auction, if you click on Show automatic bids it demonstrates how the bidding process for each auction progressed.
Have you seen this link about bidding on ebay? It is an excellent explanation of how ebay auctions work, with further really good links telling about bid increments and getting outbid over on the right:
http://pages.ebay.ca/help/buy/automatic-bidding.html
