One of the two cancelers had 10 recent retractions! Guess not much you can do, except cancel their bids. Although that's better than winning and not paying!
I had to do one retraction last year when I bid on the 71 lime mist GS . I had bid it at $106,000. I called Scott M. and told him, and then rebid. I can see mistakes like that, but too many people think this is a game and don't care.