As GDJMSP stated, this is certainly a RPM, but RPM's aren't all that rare. There are a few examples of a doubled die reverse for the 1950-D. That is a rare coin.
Rpm At first I thought I was looking at a 1950D, but after checking it again Irealized it was a 1959D. So how do I go about finding out it's rarity? I not really a coin collector, just someone with a load of coins?
There are specialty books on each coin series, along with guides such as cherry pickers. All supply dealers will carry these books. Some varieties carry a premium and some do not. Usually, RPM's do not carry much at all. Prior to 1985 the mintmark was added by hand. Many times, the mintmark was repunched due to low relief, wear, polishing, location, and many other reasons. Various size mintmarks are also common on many coins. With few exceptions, these coins will not be of any increased value to collectors.
