Is If Cupid Had A Heart a real song?

Ok, so I know that Mykayla girl preformed it on Hannah Montana, but I want to know if it's a real song because in the movie Little Miss Sunshine, while Olive was backstage right before her turn to do her talent and her dad and Dwayne were trying to stop her, I could hear If Cupid Had a Heart in the background, like one of the girls was preforming to it. So is it?