That looks perfectly normal to me, and I highly doubt it's a repro. That's very common damage found on many Genny game manuals. It's caused by the cartridge rubbing against the manual. It's just wear over time. I have it on a few manuals with games that I bought brand new in the day. The wear is in the exact same spot as yours. If you line up where the edge of the cart comes into contact with the manual when the case is shut, you'll see it hits right in that spot. Don't worry about it.