hatching rate

Hello friends, I made a incubator by myself and made two hatches. The pic uploaded is my first chick from my second batch of incubation. In the first batch i got 8/10 and in the second only 6/9. The chicks are mostly dying at the last days of incubation. I can see fully grown dead chicks inside...

Good morning my fellow "peeps"!! I am going to be setting a few eggs that I was lucky enough to be given, but I also have some eggs coming about a week and a half later that I ordered. My question is; Can I place eggs into the incubator if I already started a batch?