If they make it obvious that it's a replica, it's not quite as bad as them trying to replicate it to the point where people have a hard time telling them apart. As somebody mentioned a while back, fakes don't really hurt the companies because knife makers like CRK, Strider, Hinderer target a certain type of customers.
The people who would spend $400-800 on a knife would not buy a fake even if it's nearly like the real thing, because they know it is NOT the real thing. The people who would buy the fakes are the ones who can't afford the real thing or are unwilling to drop that kind of a coin for the real thing. So those companies aren't really losing any business because of the fakes. Those people wouldn't be buying from them anyways.
The biggest problem is when someone tries to sell a fake as the real thing.