Yeah, thats a reproduction cart.
For the most part, all you need to do is look for wires. No original board should have wires running around inside. Theres also the TSOP method to make reproductions, which is basically a programmed rom with specific assigned pinout locations so theres no need to use wires.
Those look like this:
http://i.imgur.com/OFNotJw.jpgTo be honest, you shouldnt have any issues telling if its fake or not once you look inside the cart. Its usually pretty obvious. From the outside, maybe not so easy if buddy knows how to make good quality reproduction labels.
EDIT: Heres a forum thread on NA about a couple people who bought Hagane reproductions on ebay.
http://www.nintendoage.com/auth/forum/messageview.cfm?StartRow=1&catid=8&threadid=90036Apperently one guy even went out of his way to find Blockbuster Void stickers to put on the carts after he built them. Then said he got them from a closing out Blockbuster store. Talk about Greeeeeeeeeeeeheeeeheasy! And the funny thing was, we were just talking about this a few days about if there was any websites that sold reproductions of retail games. And I said I knew this kind of thing would happen sooner or later if you could. Now Im sure smost of the fakes so far, are probably sold by the people making them themselves, but imagine if everyone could just buy a reproduction of a retail game from a website advertising they do so? They'd be all over the place.
I hope the kinda shit comes to end REAL fast!