That brings something to mind actually. If DnD are strictly 52 cards in a deck magicians (I may be wrong but I heard they don't use gimmicks/gaffs EVER. Please correct me if Im wrong) and they created smoke and mirrors with their interests in mind....why the double backer?
That's a very good question - perhaps just keeping in line with tradition from here at T11? I mean, it's only one extra card, so they could just be facilitating those magicians who do use the double-backer - which would be different of course to creating an entire deck of gaffs, a new product.