They have been faking this coin for over 100 years, way over. (In fact the original coins are even argued to be legitimate Continental issue Currency, unlike the Fugio Cent, there is no record of this coin having been authorized nor does it have a denomination, dollar is assumed.)
The originals are very rare so the odds of finding a real one is also very rare, dug or not. THe existence of the proper amount of N's or the correct or mispelling of Currency are all characteristics of of the real deal coins is die variants and all of them have been closely copied. So in Summation The only real way to tell if you have a copy (Other than it being stamped "copy" or obvious cast) Is to have it looked at. The ANA gets many requests per week on this coin. Once in a while someone hits pay dirt! I think I would almost not want to find this, because you HAVE to have it looked at but chances are slim. FAQ to Coins of Colonial and Early America