I am going based on my experiences but I am no duck pro.
That said, my Muscovy ducks often share nesting duties, but I can't comment on ducks of different breeds. As I mentioned, they rarely leave the nest once broody, and do so only for a stretch, food and water. When they do leave the nest, it is well covered with feathers and shavings. Did your ducks cover the nest before they went out?
Have you marked the eggs? If you think they are truly broody, you should be removing any new ones. Marking them would also let you candle the eggs at about 10 days to see if they are viable.
I think the fake eggs work in some cases. My chickens can be fooled by plastic Easter eggs. My ducks will occasionally push an egg out. I think they know which ones are not viable and remove them. Again having mine marked means I can check a second day so if same egg has been removed by them, I take it out.
I don't think you need to cage off a corner for them. In fact it might create more problems. How will the ducks get out when they need foot and water? If the sharing of the nest doesn't work out, one or both of them is going to get hurt. A broody duck is very capable of defending her nest.
Final comment would be regarding your location. I am in Eastern Ontario, Canada. We still have 2 feet of snow on the ground and below freezing temperatures at night. My ducks and peacocks have not started laying again. The chickens have just started. There is no way I would allow any of them to start on clutch of eggs because weather conditions for any hatching chicks would be deadly.
That said, my Muscovy ducks often share nesting duties, but I can't comment on ducks of different breeds. As I mentioned, they rarely leave the nest once broody, and do so only for a stretch, food and water. When they do leave the nest, it is well covered with feathers and shavings. Did your ducks cover the nest before they went out?
Have you marked the eggs? If you think they are truly broody, you should be removing any new ones. Marking them would also let you candle the eggs at about 10 days to see if they are viable.
I think the fake eggs work in some cases. My chickens can be fooled by plastic Easter eggs. My ducks will occasionally push an egg out. I think they know which ones are not viable and remove them. Again having mine marked means I can check a second day so if same egg has been removed by them, I take it out.
I don't think you need to cage off a corner for them. In fact it might create more problems. How will the ducks get out when they need foot and water? If the sharing of the nest doesn't work out, one or both of them is going to get hurt. A broody duck is very capable of defending her nest.
Final comment would be regarding your location. I am in Eastern Ontario, Canada. We still have 2 feet of snow on the ground and below freezing temperatures at night. My ducks and peacocks have not started laying again. The chickens have just started. There is no way I would allow any of them to start on clutch of eggs because weather conditions for any hatching chicks would be deadly.