Is this one probably a boot?
I believe the label is probably a repro. Most MS3's I've seen have had the serials scratched out. The label and case are probably non-original for the cart and judging by the other carts he has listed, I'd put my money on it being a bootleg. KOF 2004 Plus and 12-in-1 carts? These carts probably came from China from somewhere like Welink or ECL.
Definitely a fake label, font is too thin. You better ask to see the boards before you bid.
I've got a real MS3 US and it has no serials but the label is a hologram.