How can this happen to a company such as Ebuyer you ask. Well I don't like Ebuyer and would not use them again but to be fair they have presumably bought these "copied" sandisk drives from a supplier who perhaps has also been conned. It can happen to any company and there is no way they can possibly check every item that comes in except to give it a once over to check the box contains what it is meant to and the amount it is meant to.
If this drive proves to be a copy then you will have to send it back to Ebuyer for refund or replacement. After of course going through there lengthy Enote returns request procedure, then you will have a wait while the actually check the item.