Your birds are really too young to be set up for breeding. They should be at least 2 years old before you set them up. Young birds are more likely to make mistakes such as not incubating properly, breaking or eating the eggs, or killing the chicks. If they develop any of these habits, it can be impossible to break them and ruin them for being good breeders. They are already incubating wrong. One parent should sit during the day, and the other sits at night. Since your birds aren’t sitting at night, I would take the nest box down and discard the eggs, because they are no good. Ideally you should separate the pair and wait for another year to put them back together. It’s not good for the hen to be laying eggs this young. She is at a higher risk for complications like egg binding. They are more likely to do better when they are older.
I do have another concern. I didn’t understand what you meant about the egg laying. There should be one day in between each egg that is laid, so it would take 9 days for a hen to lay 5 eggs. If there was a new egg every day, then you might actually have two females, which would also explain why they are both sitting on the eggs together.
Thank you for asking Lafeber,