Looks like a meat spot, it happens sometimes a piece of the lining of the ovarian track comes off and is included in the eggs during its development. It’s normal and you can eat them. I personally don’t just because. Lol. But that’s just me.
I recently found the same thing in two eggs from one of my ducks. I had no idea what it could be. Thanks for the explanation. If it keeps happening, is it cause for concern? Would that indicate a health problem?