I offer these very often, get mixed results from my store.
Go to ebay and sign in. Go to the "my ebay" section, and look under messages. A genuine second chance offer will be listed there.
A second chance offer will have a separate item #, and is only offered to you. There is also a time limit the offer is valid for. The item should be described exactly as the original auction, and you are not obligated to buy.
I often list only one, even if I have several items, as I will get more bids. I will then give second chance offers to the next highest bidders, unless they are less than what I am willing to sell it for. I did have a guy back out seconds before an auction ended, and could not cancel his bid in time, so I would have been out, but the second bidder decided to get it.
You still have the "protection" of ebay regarding feedback. MAKE SURE IT is THE SAME GUY, as I have been offered in second chance offers, the exact same thing I was just selling-they even stole my pics.
feel free to PM me if there's any more ???