The rules are clear, it's ok to bid on any auction as long as you had the cash to cover the initial bid. Example: bid on 2 players, win the first puts you negative but you can continue to pursue the second (or third, etc). Players can make as many bid in a round as they want, it got him the player after all. Maybe he had excess tokens and no cash.

If you think an account is fake or a bot or anything but legit, you can report it direct to support. Otherwise accusing unusual accounts and bidding habits of being fake or cheats just sounds childish.