The first list is court precedence as determined by The Queen for royal occasions and can be changed at any time. The Duchess of Cornwall is currently fourth, after Her Majesty, The Princess Royal, and Princess Alexandra.
The second list is the official precedence of the Kingdom, which never changes and is the one that really counts. Here The Duchess is second after The Queen as she is the wife of the heir to the throne and next to become Queen Consort.
So officially then would the future wives of Princes William and Harry follow the Duchess of Cornwall then?
Sorry for all the questions. My 6 year old son has got into Monarchies and the British Royal Family in a big way, but things like precedence are not something I really learned much about myself.