That's just not right, AF. Contact the seller and explain the problem. I'm not sure what they will do about it, now that you've removed the rivets, but you should contact them anyway. It may be a problem that they're unaware of, and you might prevent them from shipping the wrong sheath to someone else. It doesn't matter how much you paid for the sheaths: wrong is wrong.
OK I'll let Knifecenter know.