User blog comment:DinoKev/Dupe Cards/@comment-70.15.124.227-20120520132212/@comment-5012038-20120525131847

It's great that Gree replaced your card. The person who sell you the card could be a victim himself or the person who dup cards though.

I happened to know more about the source of duplicated cards after writing this blog, his open feint name is penguin related. I think Gree is aware about him duplicating cards since they removed them during the update but I'm unsure whether he is still doing it.