All flock feeds are good for both
I used to have my chickens together with my ducks, but have since separated that because my three chickens were terrorizing my 15 ducks . It sounds funny, but actually, it was pretty horrific. My ducks were so frightened. Three of them had prolapses because...
The manna pro duckling/gosling starter is a great feed. I use it myself, but any duckling Feed even the Mazuri brand is usually not enough for ducklings to really get all the niacin they need, and some ducklings seem to need it more than others, so we always add 1 tablespoon of nutritional yeast...