It’s a bit of a captain obvious but here’s what you can do if you already have USF4 and only want the pre-order codes. Preorder the disk version from gamestop, use the pre-order code, return unopened game as new.
Well I pre-ordered and got my code already. I also already have a lot of bought dlc from some time ago, might pick up a pack or two since I for the most part have been using multiple characters still.
Course I could understand those who paid for it online not wanting to do this since they got additional codes after all to hand out to others for free.