The portrait on the left stamp looks like the same portrait of Eva Peron as on Scott 607, but that's clearly not the same stamp. Maybe Google can help?
i believe the first is from the National Savings and Insurance Fund and not a postal stamp.
The second is Cinderella to raise funds to for "The Erection of the Monument to the Shirtless" in the 1950's. Lots of details of it on the web and there appears to be a whole series of these stamps.