I just watched her perform @ Indian Wells Resort Hotel with her long-time pianist Rich Bono tonight. She sings and moves exactly as she did when she appeared in Columbo. They are regular performers there on most Wednesdays. They do take a break from time to time.
In a later scene, Columbo and Danziger enter a bar where a recording of "When the World Was Young" is playing. The voice sounds like Poupee Bocar. Perhaps they recorded it for the club scene and decided not to use it there but didn't want to waste it.