Duck eggs do better laying down being rolled over rather sitting up in a turner anyway- and for chicken eggs- you could try and find a plastic egg carton to put them in. There are only a few difference between hatching chicken and duck eggs- so if you are wanting to set them at the same times- things to remember are that duck eggs take longer- so if you want them to hatch at the same time- put the duck eggs in first then add the chicken eggs a week later- or if you have ,muscovy eggs- two weeks later since they take 35 days to hatch. Duck eggs also need higher humidity than chicken eggs, so for starting out you may want to do a run of each just to see how things go. You would most likely need to brood them separately anyway since ducklings are pretty messy in comparison to chickens.
Maybe if you post the model or brand of the incubator you have someone may be able to give you some specific ideas about how to convert it for use with chicken and duck eggs.
