Although these covers are not obviously philatelic, as in for example, if they were addressed from and/or to a stamp dealer, the person who sent them must have been a stamp collector. The stamps have been placed on the covers with care, they often have selvage, and also often the postage on the cover exceeds rates to Germany at the time. A batch of these covers came out of Asia (was it Singapore?) on eBay all at the same time. I was lucky to grab these.
This cover could match a real rate of 2.15 pesos. It's a first month of usage for both of these issues.