A couple of interesting coins, the 1927d I have no idea (maybe just die deterioration? But the 1984d is really strange I don't know if it's a real "D" or just some really wierd corrosion?
That is weird. If the second "D" was just a stain/corrosion it would be relatively flat. Is there a way to measure how "high" the D is relative to the surface of the coin?