Heck I say stick em in an incubator and check in a week and see if there is anything growing in there , you wont loseing anything really unless you like to eat duck eggs
well it's been a week so i candled them last night 5 / 10 of the duck eggs are full the rest was infetile ! i also tried to do 11 quail eggs witch i found impossible after the first one and gave up as i could not see a thing !! but cheers for your help people ..