1969 S Repunched Mint Mark?

I see some questionable things else were on the S and O on the coin. Not sure though. I've taken some more pictures. What's MD?

It looks like machine damage to the coin during the strike.
Machine damage/ machine doubling/ strike doubling/ stutter strike/ Mechanical Doubling are all terms to identify what happened during a strike. The die was normal, but when the strike took place, slight die movement or even a bounce of the machine damages the devices. Sometimes a varying differences of where on the devices this takes place. Here is an image to show you what happens:

Note the damage to the devices distorted part of the normal size of the devices? this happens a lot and can vary from strike to strike.

Note the minor differences the die made because of the die damage to the coin during striking. These are all from a same roll and you can see the same marker on each coin.
The 1968-1972 coins had a lot of this happening those years.

This machine damage can even be seen on coins that were from a hub doubled die:

Note the arrows on the last image. Usually if you can see MD on the mint mark, you can see it also on the date or on other areas of your coin. On your coin I can see it also on the reverse. Hope this helps.