I am going to dissent on this one.
The thickness of the raised inner top strut and the bottom strut is the same. You need MD metal to come from somewhere. I don't see much evidence of
DDD. There is a faint interior vertical bar. A lot of the 1960-1964 repunched D mint marks can present like
Machine Doubling.
I'm not saying that it's definitely an RPM. But I don't think it's instantly cut and dried. I would want to hear someone like Tanner or TB give their opinion. If the feature is indeed cut and dried, I would like to understand why, purely for my own education. If this were my coin, I would definitely set this one aside for further analysis, at a holding cost of five cents.