Tricked my local game store

Remember that Metroid Prime: Hunters demo that came with the first shipment of DS'?
Well, I was a bit low on cash and I wanted to buy a new Wii game (Prince of Persia:Rival Swords) so I decided to trade in some old DS games. They were:
Tony Hawks: American Sk8land
Metroid Prime Hunters: First Hunt
Super Mario 64 DS

So the cashier accepted the two real DS games, but when she came to the demo she called over the manager to ask if it was acceptable. He said " Mertoid Prime ( yup he said Mertoid)? Check it on the computer" She typed in Metroid and up came the real game! She accepted it and gave me 20 euro!