If you do a Google search for "683422223143", which is a barcode number, you get four entries in the search results:
The first entry is the page that we generated at TheBarcodeRegistry, using information the barcode owner entered about the product associated with that barcode.
The second entry is an internal page of ours that shouldn't have been indexed, that I've blocked since with noindex,nofollow.
The third and fourth entries are what puzzle me. Neither of these have the search term: 683422223143 . So I'm thinking that Google must have looked at the contents of the page it got from us, saw that 683422223143 was about the book "Drawing Dead" and then done a further search for that term, to turn up entries three and four.
Does that make sense, or is there a better explanation?