Hmm, did you get caught by MDD? in 1972, one of the Master hubbing dies had been doubled. This produced a group of working dies, of which some received the D and S mint mark mass producing the MDD for all mints. Think this is a good example of this.
This is not the die you think it is. It is just one of the 50% master die doubled examples. Look at the shape of the DDO and the mint mark location. Markers mean nothing without first the variety, the mint mark location, then the variety.