This is not a problem if you start the chicken eggs 7 days later. I do this all the time when hatching chicken eggs with guinea or turkey eggs. Lockdown becomes the same time for all of the eggs.Eggs need to go into lockdown when ready to hatch. No more daily turning of the eggs.
Chicken eggs hatch at 21 days.
Duck eggs hatch at 28 eggs.
Lockdown and hatch timing are out of sync.