Hi,
The exact same thing happens here! I have 3 broody Silkies right now (all in one nest) and then the others also try to lay in the same nest.
One time, I saw one of my Leghorns trying to lay with the Silkies and she couldn't fit in there very well. So she spread her wings over the Silkies so she could fit. It really looked silly with the Silkie's little heads sticking out, kind of like they were the Leghorn's babies under her wings!
When the Leghorn finally laid her egg, one of the Silkies immediately "stole" it with her foot and rolled it right under her. The Leghorn got up, looked around, and appeared to be very puzzled as to what happened to her egg. It was like she was saying "Where did it go?" I had a really good laugh over that one!
These chickens sure can be funny! Genie