My duck is nesting on a couple eggs, Do they look okay?

[Angel9_999]

My duck decided to start sitting and I didn't notice at first she had a hidden nest. She had some of her eggs but mostly my other ducks unfertilized eggs. So I took all the unfertilized and left her with her two which is in now constantly sitting. I am curious if these eggs look correct. I know Egg #1 looks pretty good. My question is on Egg #2. From the beginning when I first found them the egg was discolored and shadowed enough it was very hard to candle and tell if veining or not. But it has gotten darker and darker. That I can tell by candling. But I am not sure if its a good egg or just an egg going bad. First pic is Egg #1 4 days ago.

 

[sourland]

To me both look fertile, but the second is way further along than the first.

 

[Angel9_999]

Okay, if the one hatches soon will she continue to sit until the other hatches as well?

 

[Angel9_999]

Will mama duck know when an egg is bad? This morning she took one of her eggs and crushed it and stuck it in her water dish. It didn’t smell good. Smelled rancid. Please help I want to make sure she won’t do the same to her other egg or if I should pull and incubate.