Still trudging thru my coin stash and came across a ‘91D and a ‘91P dime that I put aside for whatever reason. Well, I came back to them and weighed them, only to find that the ‘91D weighed more than 2.27 grams...it weighed 2.31 grams. The pic of the two edges, the ‘91D is on the left. Possible reasons for such a weight difference? Thank you.