doofenshmirtz’s mental process i think

Mans was literally so respectful he never assumed every turquoise platypus he met wasn't automatically going to be the one and only turquoise platypus he's ever met 😂😂😂

I think it’s very sweet that Perry the Platypus recognized that the poor dude is effectively platypus-face-blind (and possibly colour-blind as well), cannot tell if a random platypus is or is not Perry, and is never going to assume in case it is a different platypus because that would be RUDE - and therefore carefully puts on his hat every time, so Doofenshmirtz knows who he’s talking to. 

That is some prime Politeness-Between-Nemeses right there. 

To be fair, the tri state area apparently has a LOT of platypuses.