I cannot get it to blow up and save but I have blown it up and can see it on my computer. so if you can, go ahead and download it and blow it up and tell me if i'm seeing what i'm thinking i'm seeing. Not to be pushy, I'm just asking if it's what it is.
Even when I blow it up, the pixelation makes it hard to see. It does look like there is doubling on the mintmark also? If it is doubled also, you can bet it is machine doubling as the mintmark was punched in after the hubbing. The extent of doubling in the very rare 1970-S business strike is such it would be very visible even on your photo, so I would rule that out. There were several proof DDOs, but this doesn't look like a proof in the photo. SO the best bet is machine doubling effect. Jim