This group is for the stamps in group 1 overprinted with Ministerial official overprints. The base stamps are the 1c, 2c, 3c San Martin Green, 5c offset, 10c Rivadavia Red, and the 20cJMG. I am including the 20cMG in this group for now even though it was issued sometime in 1936.
I find that there are four variations of the 10c Rivadavia Red stamps as issued with these overprints: each type (I and II) was printed in dark colors and then in lighter colors from worn plates. The Type I was mostly printed in dark red, and I am guessing that there aren't many type I's in light red (I only have the M.M.). There is the need to look through a bunch of these stamps and sort out the ones that were actually issued.