This is an exciting and fascinating new discovery. An unknown type of error until this discovery piece. It was first spotted in circulation by a woman sorting through her states quarters looking for errors. It has changed hands several times and finally found it's way to ANACS for certification. ANACS authenticated, certified, and graded it MS 64. It is a dual date (two different years, and also two different centuries, 2000/1999). It is also a dual state (Massachusetts and Georgia).
This mint error is a 2000-P Massachusetts States Quarter struck over a struck 1999 Georgia States Quarter. The U.S. Mint has produced nine different States Quarter designs over a one and a half year period, with almost nine billion produced. This is the first and only known example of a dual date and dual state. This new discovery was featured in the September 25, 2000 issue of Coin World.
This new discovery was consigned to Byers Numismatic Corp. from a well known major mint error collector. Mike Byers then sold this dramatic error to another mint error collector.