Thank you for the additional information. Do you have a nest box for them or is this in regular finch nest (a covered straw-type nest with a hole entrance)?
Have you been checking regularly on the eggs?
About how old are these two?
Are you absolutely certain you've got a male and female? Two females will be able to lay eggs (although they won't be fertile).
Many have forgotten this truth, but you must not forget it.
You remain responsible, forever, for what you have tamed.