1960-D Small Date And 1970-D Date Doubling

The 1960-D is a small date. the large and small date Denver coins are almost the same value. the Philly ones in the small date are the more valuable ones for the year. The other three are about the same price. Why? Fewer coins made with the small date Philly Cents.
The 1970-D Cent is just that. a 1970-D Cent. The mark that you mention is just a gouge or distracting mark. I notice on the site there is a great searching for over mint marks or mint marks or letters that some feel are there. Why would an over mint mark happen? If a mint created a die and placed the mint mark on the die and sent it on to another mint as they need some to complete there runs. So the second mint adds their mint mark usually over the first mint's mint mark. There were times when this happened. But to find/search for one on a year that no such exchange took place would be unnecessary. Other wise anything larger/smaller than a mint mark could not happen. If the mint didn't place it there, it would have happened from damage/wear/gouges from cleaning/or even something I haven't mentioned. Seeking something that couldn't of happened is just spinning your wheels. Many times we look too hard for something that isn't there and couldn't be there. So when you have questions, ask them. No one wants to be waiting for a bus that doesn't come down that street. No criticising anyone, but it seems to be something that happens here from time to time.

Can you post another pic of the 1970-D with the light from a different angle. I just want to rule out the double image/glare on top of the 1970 date and inside the "0".

I see doubling on the date, but it appears to be Machine Doubling at best since it only shows on the top part of the date - it's missing the corresponding doubling on the lower parts of the 9 and 7. The 0 seems to show a bit of doubling, but all the doubling is also flat which I've begun to associate with MD.