Maybe you guys can help me. I was looking through a bunch of 2009 Native American dollars and I noticed one that has what appears to be majority of a 2 which is upside down next to the E in E Pluribus Unum on the rim. Is this a common occurance with edge inscribed coins? Was just wondering. The photo sucks, but under a 10X it is clear as day.
So what you describe sounds similar to the 2009 NA dollar that I have - mine has an inverted 2 on the edge as well. Unfortunately, I don't think it counts as an error - technically, probably damage. If you examine the '2' carefully, is the number impressed into the metal? If so, the reason is because another coin was pressed so hard against the edge that the incused '2' from one coin impressed the image of a '2' onto your coin's edge. I have found many such partial and full examples on the edges of NA dollars and the presidential dollar series. Unless a market develops for such a phenomenon, I don't think it will be worth any more than face value.
Sorry to be the bearer of bad news, but they are interesting finds nonetheless.