New Member W/First Posting - 1979 S/D Proof PDSS DDO Washington Quarter

to the forum and the hobby!

I do not think this is a doubled die.

A doubled die occurs when the design was hubbed into the die multiple times, with at least one of the hubbings being misaligned. Up until 1990, the mintmark was added after the design was hubbed in, and therefore after a doubled die would have occurred. Because of this, a doubled die would not affect the mintmark. Since the mintmark on your coin has identical doubling to the rest of the coin, it cannot be a doubled die. Rather this is Machine Doubling, when the coin moves while being struck creating this flat, shelf-like doubling.

Also, since proof coins are purposely struck multiple times, Machine Doubling is extremely likely.

You've come to the right place for learning about coin errors and varieties. By looking at past posts and threads, asking questions, and having a little patience, you can surely learn how to differentiate from a doubled die and Machine Doubling (also abbreviated MD) and how to identify errors and varieties.

Hope this helped.

Also, error and variety-related questions should be posted in the error and variety sections (Dorado posted the link).

Welcome to the Forum. You've come to a phenomenal place to share and learn.