I just looked at a few "stamps on" postcards on
ebay, not having any myself here, and they look similar to yurs but yours does have differences I think.
The background bumpy darkened area on your card is different, the shadows under the stamps and coat of arms label is different, but the stamps do have the shdows under them, making them look more real than flat litho printings of stamp replicas.
However, in the upper left corner there is a similar number and initial (probablu the abbreviation No.) that does indicate one in a numbered series of created postcard designs for countries issuing stamps around the world.
Is it possible to do a closer, higher resolution scan of some of the stamps on your card and the No. ~~ in the top corner?
Here are a couple of similar ones from
ebay:
Uruguay:

Germany:

Very collectible.