This looks like the same type of DD on the State Quarters on the bottom of the ear. I don't see this listed anywhere. Also noticed what is probably Die Deterioration Doubling on the IGWT.
Yes, it's probably Die Deterioration or Machine Doubling. I found a 1993 P last week, something similar to yours. I've been wondering about. I'll post it in a minute.
Yes, I'm guessing DDD. I'm not an expect. Let's wait for others to chime in. I'm going to post my 1993. Let me know what you think.