Ethiopian postcards

This was my first really puzzling thing I’ve received from Postcrossing. I got an envelope with a Czech Republic ID number on it…

And inside were three postcards from Ethiopia. One of those cards was written on, informing me that enclosed are African cards.

The cards themselves are gorgeous, and I’m happy to have received them, but why three? And my profile specifically states that I prefer postcards sent “free,” not in an envelope, so I can see the stamps with the postcards. Hmm. Oh well.

http://www.postcrossing.com/postcards/CZ-188488