lol i feel so dumb !! why do they produce the mandolin back then ?
Because the USPCC has recently forbidden companies such as Ellusionist and Theory11 of making gaff cards and editing the copyrighted back design, so a magician (I believe his name is Richard Turner) produced this deck of cards that looks very similar to laymen, but you can make gaff cards for this deck without infringing their copyright.
The problem was slightly more complex than that. The copyright on the Rider Back EXPIRED - it's nearly 125 years old. Other companies overseas tried replicating the back on their own cards in an effort to profit off the popularity of the design. Bicycle's legal team felt that a solid legal defense to protect against such attempts was to not alter the back design, out of concern that it would dilute any trademark defense in court. So any requests to print alterations of the back design, as well as the unique Joker and Ace of Spades designs, were declined.
Obviously, magicians weren't terribly pleased about this. USPC worked with a small team of magicians, including Richard Turner, on designing a deck that was close enough to the Rider Back without actually being the Rider Back. They tested some designs with focus groups and found the Mandolin Back to be almost indistinguishable to most spectators. They designed it specifically so the back could be altered - it's a new design, thus covered under new copyright laws, so legal defense against forgeries is solid. They also made them traditionally cut, to make them shuffle and faro face down with ease.
that explain why arcane gaff deck is mandolin back
The ARCANE deck has an ARCANE back, and so do the gaff decks!!! Please, you make my brain hurt... Opinions and free speech are great, but I beg of you, do a LITTLE research before you start sounding like you don't know what you're talking about. I don't claim to have exclusive rights to being correct, and I welcome corrections when I'm wrong, but I can tell the difference between Mandolins and Arcanes...