A friend has been offered this cart and it seems to be a prototype but I'm not sure what the extra board is, any thoughts?

Is it a dummy game like it says on the front right of the board?

looks crazy

subbed to see what you find out

Part of me is getting a Super Noah's Ark 3D vibe from that like it would be using the bottom board to patch through. I guess your friend would have to plug it in and test it?

The date on the cart is 28/05/93 and its pal version, so that is several months before it's release from my understanding.
The guy that is selling doesn't know anything about or has the means to test or open it up. It's not really my area of expertise though.