Why did this $20 bill sell for $396,000? Because a Del Monte sticker got stuck on the paper before it was printed

The Del Monte Note is highly prized among currency collectors. It's a US$20 bill with a Del Monte sticker affixed to the paper before the bill was printed. The seal and serial number are printed over the label. In 2010 Heritage Auctions sold the bill to a lucky bidder for $396,000. — Read the rest