This is a rather startling duet. Melua was born in 1984 and was twelve when Cassidy died. There was a program called “Duet Impossible” which aired on television channel BBC One in the UK some years back. It digitally matched current performers with an artist whose work they considered a major influence, and Melua felt Cassidy was one of hers. I imagine the tape of Cassidy was from one of her performances in DC.
I have to thank Donald Steiny at Facebook for pointing me toward Katie Melua; I’d never heard of her till today, but she can really really sing. Cassidy I’ve known about for years.