This pair of covers shows that the rates remained the same, but the stamps changed between 1935 and 1936. The first cover is from October 1935. Between October 1 and December 31, 1935, the new lower values could be used with any stamp from the previous, San Martin, issue. This cover is a 1.15 pesos rate to Germany Via Condor.
The second cover has the same rate to Germany, now in 1936 with all stamps from the then new issue. All of the San Martin stamps were demonetized January 1, 1936.
