Wow! that was unexpected. I have a hen which laid one egg which was larger than a goose egg at 93 grams, a large starts at 53 grams. It was actually two eggs fused into one. I have not heard of laying two eggs a day.
Eggs are made up of mostly water. How is her water supply? Are there other hens? Have their eggs been affected as well? Has this hen gotten into something like fruit? Some people say fruit doesn't affect them but others say it can. I don't know.