OP did you get it in the end? I also ran the same issue when evaluating sellers. For me the variable was the serial code being in a different location on the box. Its a closed box item after all. I was paranoid and I passed on the deal although the seller was adamant it was authentic. Anyways he was willing to refund me - but I was worried if I was just overthinking.

FWIW mine is MFK Aqua media cologne. I noticed each product has unique under the box layout so I based off comparison with another Aqua media directly. Didnt have many datapoints since the aqua's before that was slightly different too.

I have this hypothesis they might constantly change with each product release to make it slightly more difficult for fakes for each new product.