The Other Hilton Sisters.

Chained for Life (1951) [wiki] is an exploitation film featuring Siamese twins Daisy and Violet Hilton:

It features several vaudeville acts, including juggler Whitey Roberts, a man doing bicycle stunts, and a man who plays The William Tell Overture at breakneck speed on an accordion.

The movie incorporates aspects of the twins’ real life, including their singing act, a futile attempt by one sister to obtain a marriage license, and a publicity-stunt marriage.

In this clip, you get to see the twins sing in a vaudeville act: Hit play or go to Link [YouTube] – via The Human Marvel