These were pulled from about a full box and was averaging two 2021P's per roll. There were many that were such a late die stage, I could not tell if the anomaly was there or not, so there could have been more than the six I found. I have not had time to look at each of these to see if they were from different dies but given the small sampling and the number of these I found, I would say you are correct about the working hub.
The pics are not as good as yours but get the point across.






The pics are not as good as yours but get the point across.






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