According to Bustle, who was one of the first entertainment news outlets to spill the beans back in 2017, Hilary Duff’s sister Haylie had a special cameo in the “Lizzie McGuire” movie, but it’s not what you might think. She never appeared on screen herself, but she did make her presence known. During the scenes where Hilary played both herself and Isabella, whenever the two (“two”) would sing together, Hilary was in fact not vocalizing for both versions of herself. It was Haylie who lent her pipes for Isabella.
When you think about it, this move makes sense. We’re no sound engineers, but it seems like having one person’s voice doubled for the same song would make it hard to sound like two different (yet physically identical) people were singing at the same time. And Haylie wasn’t just chosen because she happened to be the sister of a famous singer/actor. She actually had (and still has) the talent to fill the role. The Bustle piece mentioned earlier outlines her many vocal accomplishments, including a recorded duet with Seth McFarlane. These days, however, she prefers to live a pretty low-key life. Instead of singing and acting, she now runs a blog called The Real Girl’s Kitchen and also designs for and manages her own clothing company called The Little Moon Society.