Just noticed this the other day, if you have a bunch of chickens on your home street incubating eggs, and use the chicken stick to modify their radius, they all stand up and start walking around, but keep giving the incubating messages. At the end of the minute they do actually deliver chicks/caterpillars/piglets, however. I noticed this AFTER I incubated my eggs, so I didn't have a chance to check to see if you could actually incubate a second egg whilst the first one was still going.