The randomized letter/number combination codes found on Coke products can each only be redeemed once. These number-only codes that come out every so often are universal and can be used by everyone until they expire.
By the way, that very last code actually lets you choose between a Pirates ringtone, music download, or storybook excerpt. In case anyone is actually interested in more than one of those, here's a direct link
to the story, so you can read that and still be able to get your ringtone or download.