There's an online Copperfield Wiki that also claims it's Claudia even though David Copperfield looks mighty young in the photo. But according to Getty it's from 1984 which means it's definitely not Claudia
https://www.gettyimages.fr/detail/photo-d'actualité/magician-david-copperfield-performs-as-his-assistant-photo-dactualité/693509150