I do not trust eBay sellers when it comes to MAC stuff. So much of it's fake. Check the feedback, if anyone bought a fake from that seller, they'll probably have some negative feedback.
ETA: Okay yeah, looked at the other auctions. The other duos are in colors the actual mineralize duos DID NOT come in, like black and gold. There was a black and WHITE duo, but not black and gold. This seller seems very dodgy, and the buyers don't seem to realize.