i personaly wouldn't have paid more than $2.50 for the two. i'm just spoiled by the cheap prices of my coin dealer.
Might be my imagination but the D on the one on the left appears to be a micro. After the discovery of the 45 micro S people started looking at all the Mint Marks on Mercury Dimes and other micro started appearing.
Also, note if your photos are correct one of your dimes has a slight rotated reverse. No big thing though. Merc Dimes are famous for that. I would think about 20% are slightly rotated. Never could find out if it's the reverse or the obverse that is rotated. You would have to place it in a 2x2 or something, then turn it over to notice a slight rotation. I've got Merc Dimes that go from slight to almost 160 degree rotations. Also, some rotated to the left and some rotated to the right.