Although both repertoire sharing and individual variation have been studied widely in male solo song, few studies have investigated these aspects of song in a species that performs complex duets. This study examined song repertoires of both males and females of the plain wren (canebrake subspecies, Thryothorus modestus zeledoni), which performs antiphonal duets, and tested for patterns of repertoire sharing at the level of the individual and of the pair. We suggest that both males and females of the plain wren develop their phrase repertoires by direct imitation from other individuals of their sex, but that males, who may exist for a period as ‘floaters’ after dispersal, learn their songs from a wider pool of tutors than do females. In contrast to considerable individual repertoire sharing, whole duet types were very rarely shared between pairs, despite the potential for this to occur. This suggests that duet types are developed within the pair without reference to other pairs and the implications of this for duet functions are discussed.