This is as simple as a confrontation gets - two IDENTICAL back designs, in different colors.
Zen Kok's Bicycle "Gold Seal" New Fan Backs get the name from the gold sticker seals applied to the tuck box lid. Black and "white" (inverse black), with a matched set of gaffs - one has a blank facer, the other has a double backer with both colors, both have the "0 of hearts" card for performing certain romantic card routines. The deck uses an AoS design which is roughly a century old, straight from USPC's archives, and identical modern jokers. 5,000 black decks and 1,000 white decks made. Classic-style box with standard tuck box stock and finish, while the cards are Air Cushion on Bicycle stock.
D&D's Bicycle New Fan Backs have a nearly identical appearance and come in navy blue and vintage red. Modern AoS, modern jokers, no gaffs and a pair of D&D ad cards (they do have the deck backs on them, so the patient magician could alter them to be a double backer or, with extra cards, a pair of blank facers or any other other face. For the faces, they did something unusual with the face coloring, specifically the reds: the blue deck has standard "Bicycle Red" while the red one has a darker, "casino" shade of red which matches well with the card back. Box is matte finish and "vintage-style classic" with some gold-foil accents. Print run size is unknown, as Dan and Dave rarely reveal this information - best guess would be somewhere in the range of 10,000 to 30,000 per color. The stock for the cards is probably Bicycle, but you can tell by the smell that the finish is Magic Finish!
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