As was mentioned in an earlier article here https://duelevolution.wordpress.com/2007/08/17/patch-from-konami-on-17-august-2007/#comments it is speculated that NPC duel will award cards.
However a new quote has appeared which mentions this:
“Oh Yeah! Do you have this tracksuit? I asked Miss Dorothy at the store and she told me that they are always sold out… Do you wan’t it? I’m sorry, but it’s my spare. I hope you don’t mind. No don’t worry about it. It’s only for girls though!”
This was probably added with the new academy store npc shown below.