In the Spyderco brand they only copy the Southard , Military and the Paramilitary 2 (they do a couple of others but not nearly as much as those 3) . I actually have a fake Paramilitary2 that I bought knowing it was a fake . I had read so much about the PM2 and wanted to try one (size wise and feel in hand) without spending the $150 on a real one , in case it just wasn't for me .
I did a lot of reading up on the fakes and what to look for and then went about looking for a very well made copy of the PM2 . Now I want to say here that I think Spyderco makes a great knife and I'm NOT putting them down in any way . I had a Spyderco Native for years and loved the knife . Sadly I just lost it on a recent late season camping trip . But I have to say that the fake PM2 I have came shaving sharp (literally) and works so well and so smoothly that I personally can't see spending the extra money for a real one . Just being honest here , not looking to get BBQ'd .
Like others have said , they work so hard to make the copy exact that they really ARE pretty much as good . With the exception that I'm sure they must use a lesser steel in the blade . But the one I have is supposed to be D2 and weather it is or not it doesn't dull easily .