Currently doing this map right now with Bismarck. Already have Yuu, but my priority at the moment is Prinz Eugen. Once that's over with, Graf Zeppelin is next.
As long as the duplicates are not in the same fleet, it's allowed. There was an image I found that had Fleet #2 composed entirely of duplicates from Fleet #1 in a Combine Fleet set.
Just made this image a reality, when I saw this image I really wanted to accomplish it as my goal for this event. First Graf, then Yuu, and finally just got Pudding.
