I’ve seen store SOs with the horse shoe stamp.
To echo everyone else - yes stores can do SOs. Normally they are placed by the SM and can reflect their taste (there’s one store I know whose SM loves Rose Poupre and ordered Rose Poupre w/ another color multiple times lol). Also we’ve had people share the story that since their (customer) SO turned out very pretty, their SM placed store SOs of the same colors afterwards (which made the customer a little unhappy).
I also agree that the caramel/lime combo is an existing verso combo that’s not necessarily an SO. Regardless though it’s very pretty! I wouldn’t worry about whether it’s SO or not. Enjoy the bag!