The question that comes to mind for me is "how do you keep the owl away?" Obviously, it could become a problem, especially if it decides to make a nest somewhere else in the loft, and perhaps it hatches some out....well now it's looking for food....I would be trying to find a way to discourage it from coming into your coop if indeed it is an owl.
No chance it's just a double yolker from your guineas?
No chance it's just a double yolker from your guineas?