Hi,
Obviously the bird that isn’t laying eggs is a male. The cere is not always an indication of gender in parakeets. With many color mutations, the cere is the same in males & females. Hopefully you are offering a nutritionally balanced diet like pellets, and not a seed diet. They also need leafy greens, chopped veggies and since they have chicks, they need an egg food daily. This can be a commercial dry egg food, or you can cook an egg with the shell washed, crushed and cooked with the egg. They need a lot of food right now to feed the chicks. If they do not have enough, they will stop feeding the chicks and let them die.
Thank you for asking Lafeber,
Brenda