Today was A new chicken experience

[TexasSam]

While it's not uncommon for a broody to steal eggs from an other box, I believe the un marked egg was deposited by an other hen. Usually, broody hens stop laying before they start setting. The issue of her moving from one box to an other while she is setting a clutch of eggs is why many folks keep their broody in the coop, but blocked off from the rest of the nest boxes. I have a broody cage set up. Currently, it is open and the whole flock uses it, but if I have a spring time broody, I can block it off, and give her an area that is about 2.5 x 4' with outside access.

She didn't move from her clutch she was trying to take over A different hens clutch. She was unsuccessful so she decided to start her own lol. Plus I kept moving her off. Today she is back on the first clutch with the other girl. She isn't giving up

 

[Flashpoint]

You are not crazy. Mine have moved eggs from an upper nest to a lower nest.

They are better problem solvers then one would think.
The miracle is they move them without breaking them.

I had a Muscovy duck hen steal two eggs from a Cayuga hen - and carried them over 100 yards away to her other hidden nest. Oh yeah, those birds can think!