Why do I have duplicate cards, and what are they good for?
Duplicate cards, or DupliCards, are cards you have more than one of in your album.
This happens because even after completing a set, you may still get some of its cards in packs.
Duplicate cards can be traded with friends for other cards you need or swapped in the DupliCards section for various rewards, which could be a combination of Gems and Bonus Cash.