Great stamp - and an unusual perforation pattern in the middle - is that on a lot of Portuguese stamps?
I don't know if it exists in all the Portuguese stamps, but I have received a lot like that.
This is what Ângela (the sender) has written: "The perfuration you see in the middle is the shape of Christ's Cross when the stamps are together (before separating them). It started to be used on portuguese stamps in 2010 and it gives more security since that kind of perfuration is more difficult to falsify. :)"
Thanks for the info!