Absolutly correct.
Some of the counterfitters use copper tools, and the Native Tribes from the North brought copper nuggets with them to trade for the flint/chert, and used copper to knap points.
I use copper tools to knap, so I have to assume the carbon dating can see modern copper vs older copper?
Not really, there are other methods to help detect though. Natives did use some copper as tools (from Great Lakes Region), but the copper is a bit different than the copper boppers that knappers use today. Needless to say, fraud plays a huge role in the artifact market (as with anywhere there is money involved). Most reproductions / fakes aren't too hard to detect, but there are some fakers who are really good at what they do. I deal with those people on a regular basis, and I have to admit that I do have to chuckle to myself when I hear some of the stories...they always have a story, always.