So, you will each be getting one duckling and want to have them together sometimes? I am assuming by your question that you and your friend aren't roommates. Any change in flock dynamics (introducing or removing members) is stressful for the animal.
Ducks aren't dogs. Sorry, I'm not trying to be rude or nasty, just honest. It is unlikely that ducks that are raised/housed seperately (whether male or female) would do little more than fighting when one is brought into the other's territory.
Single ducks require a LOT of work and commitment by their owner. Ducks can live 15 years so it is also long term. But duck's are flock animals and do best with a constant companion, 24/7. Many breeders and even feed stores won't sell just one duckling for this reason.
I would advise researching a bit more before deciding to get a duckling.