I'm a little confused here but one thing I wanted to poinnt out that confused me at one point was ebay used to show the actual bidders bidding on an item so for example if your theebaydude and your the highest bidder the bid history would show theebaydude. Ebay a while back however made all this anonymous so that even though your name is theebaydude in the bid history it would show like "dcf284" Thats not actually a persons real ebay username its just a fake name they plugin there I'm guessing to keep things anonymous. It's possible this is waht your seeing and its not the same person buying.
If you are the one conducting the auction the buyers real screen names will show when you collect on the spot that says
"12 bids" or "2 bids" or whatever.
If you are just someone watching the auction (perhaps as a potential bidder) if YOU click on the "12 bids" you will see a readout that might say "5 bidders, 12 bids" and THEIR names would be coded such as "a****x" for one bidder and maybe "z****y" for another. It would ALSO show that the first one had maybe a feedback rating of 27. Maybe the second one in my example had a feedback rating of 162.
If (as the original poster here said) he (the original poster) had been tracking this seller and his potential buyers he MIGHT be able to assertain that on auction #2 which he was also watching that a bidder with the 162 feedbacks was bidding on the 2nd auction as he did on the first. Sure the 162 rating guy will have a different code name in auction 2, but now a history is building. In auction 3, 4, 5 (as tracked by the original poster here) that bidder with 162 is still going to stand out from the crowd of other bidders.
As to WHY this is proceeding as it is, that's ANOTHER question.