Probably not in this case, but shill bidders have been known to Buy their own auction once or twice to raise the market value on something.

Most of the private auctions I've seen for chips (once again, may not apply to this one) are because the seller doesn't want people who know better to contact the potential buyers. Especially when someone is selling questionable chips.

Second chance auctions could be another reason.

And how about this old trick. You have an associate buy it so it looks like a real person took delivery, then they can sell it later, at a "loss".