I posted some pictures of what my deceased eggs look like:
https://www.backyardchickens.com/gallery/albums/deceased-muscovy-egg-2.7428900/
https://www.backyardchickens.com/gallery/albums/deceased-muscovy-egg-1.7428899/
Important note:
Do not assume that all discolored eggs are dead, because...
Welcome to BYC! When I see that bruising and discoloration in my duck eggs it usually means the egg has died. Can you post a picture of the eggs being candled?