Broken eggs in brooding nest

[MJJenson]

Our Fawn Runner went broody, much to our surprise, but I have discovered broken eggs among her nest. If they didn't stink, I wouldn't find them. I have to clean out the nest so there isn't bacteria. Does she break them? Is a hen maliciously doing it while she's off the nest? What's the scoop?

 

[sourland]

Another hen may be trying to access the nest or a drake may be trying to breed her while she is on the nest.

 

[MJJenson]

I considered that as a possibility. Another hen is a strong possible. Thanks!