Calm down. It's probably just a mating thing. They just act stupid in front of the girls, and they think theyre being totally cool. It like "Waaah, lookit me puff up so big an go runnin, chicks, er, ducks"
Now I'm guessing the girls wave their heads around diagonally, and make a "kah eh kah ehck eck" machine gun noise too?
Different breeds of ducks mature at different times, and it might just be a spectacular coincidence. If they are active, eating, friendly and alert, walking normally, and mating as usual, you have nothing to worry about.
See if you can get a vid though. We can start a duck afv.
Edit: remember, ducks have the original down coat. They also have a very high body temp(duck chemistry fact: ducks body temp is around 100). They are warmer than you might think.