I'm sure it is, but I have never done it.
I have mixed chicken eggs with other duck eggs (ancona, welsh harlequin, blue swede) and had a good hatch.
I have also mixed chicken, button, and cortunix quail eggs with good hatches.
I kept my humidity between 35-40% until lockdown... then bumped it up to 65+%
I had 3/4 hatch.
I kept the humidity lower since I had only 4 duck eggs, but about 60+ chicken eggs in there.
You should get a 2nd opinion on this one.