Perrin was leader and main arranger; she added lyrics to jazz selections. The name was derived from practice of superimposing two separate recordings, leaving impression there were 12 singers. The group enjoyed some notoriety with sessions featuring backing from American guest stars like Quincy Jones, Benny Bailey, Dizzy Gillespie and Jerome Richardson. Perrin led second vesion of the group in 1965; when she became ill, Jef Gilson tried to hold band together, but they split in 1966. ~ Ron Wynn