They will hatch at different timesif you have a large breed of geese. I incubate turkey and chicken eggs together sometimes. I just don't turn the turkey eggs for the days my chicken eggs are in lockdown. I've had a lot of success doing that.
You can, yes. They might hatch at the same time or they might hatch at different times. Guineas can hatch from day 26 to day 28, and geese generally hatch between day 28 and day 32, so there is a little overlap there.
The only trouble you might run into is the higher humidity while the guineas are in lockdown might impede the moisture loss of the goose eggs, but probably not really since it wouldn't be that much longer that the geese would be in higher humidity than normal.
I'd keep turning the goose eggs during the lockdown of the guinea eggs right up until you get your first pip on the guineas.