But... the number of Dukes is unlimited.
You are not limited by the numbers of Dukes present in the game.
The prior edition has 6 Dukes, the later edition has 7.
There is no limit to he number of dutchies you may have.
The Dukes are just a convenient visual aid.
If you run out of Dukes - use something else.
Thanks for the quick answer. I would have never thought that the Dukes were unlimited. Why otherwise would you ever not claim one that you could? The rules say you can claim a dutchy at any time (new edition English rules). In what case, if they are unlimited, would you not claim it as soon as you had 2 adjacent Knights?