A misplaced date occurs when the date or digits of the date are fully or partially punched into the legend, devices, or denticles, even one digit, is found on the coin where it does not belong. Misplaced dates are usually referred to as MPD's. These also are commonly referred to as "blundered dies".
During the 19th century, the date was punched into the working die as the final step in its production. The working die was first annealed to soften it, then the engraver took a steel rod with the raised image of all four digits of the date on it, placed it into the working die and struck the metal rod with a mallet. Sometimes the engraver struck the date punch several times into the working die, to get a deeper impression. If the engraver made a mistake, such as making two images of the date in the working die, he might use an abrasive and remove the unwanted images