The 196 looks like typical MD to me but the 8 has me stumped. Looks like a smaller 8 under a larger. Almost like a re-punched date but I don't think they've done that for a long time. Curious to see how it is called.
Its MD. Bad time for the San Francisco mint machines,. The die might skate several times, I have seen a lot of 3 impressions, but not 4 yet. The only way you can tell is to look at it from a side angle and then you notice the flattened areas. You maybe able to see a little of the MD also on the date on the tail of the 9s and bottom of the 6 ( 1969-S)