Both children are pupils at Thomas Clarkson Community College.
One parent of the first child was sentenced to six months' probation and was ordered to pay £150 costs by Peterborough magistrates. It was their second similar offence.
Both parents of the second child were each fined £250 and ordered to pay £100 in costs. They both failed to attend court.
It is unknown how old the children involved were.
Principle Maureen Strudwick said the college wouldn't hesitate to prosecute parents if children missed school:
"Sadly, a minority of our parents do not appreciate the importance of good attendance at college and the effect it has on their child's education.
"It is at this point that the college will not hesitate to prosecute parents if they fail to engage with the college and ensure their children attend on a regular basis. We would like to thank the Peterborough Magistrates Court for its continued support in helping us to raise standards and improve the life chances of our young people."
The college has been approved to become an academy from April next year.
Do you support convictions of parents who fail to make sure their children go to school?