My zebra finch laid 2 eggs and is sitting...?

Eggs can be released by the female over the course of a few days in most animals. (i.e. runts are not actually smaller but rather younger than their siblings) In birds, she may continue to lay eggs over the course of the next few days or she may be done completely. Just keep an eye on her for a few days and if you notice any behavioral changes (not eating, difficulty moving, lethargic etc) call a vet asap