I recently played a game where I had melee macchiato as one of my first perks and at round 15 I did the Richthofen side Easter egg where one of my teammates had got a random perk power up. I didn't notice til after I completed the side quest that it had duplicated my melee macchiato perk and after buying all other perks it didn't go. I'm not sure if it gave me a double bonus on having 2 of them at the same time as I was 1 shotting zombies with the katana anyway.