In rare cases knockoffs can make it into legitimate shipments from the manufacturer, due to workers at the factory producing inferior cards during ghost shifts or taking faulty cards that were supposed to be thrown away and selling them anyway, things like that. Most commonly happens with Kingston, but it could in theory happen with any brand. It's pretty rare for that to happen though. I don't know if that's what happened here, but anyway, Amazon's return policies are so good, I wouldn't worry too much about it. The chances of getting a fake card are still way lower when buying from Amazon themselves.