"Janet and MJ Duet" is a placeholder title for an unreleased duet written by Bryan Loren for Michael and Janet Jackson and intended for the Dangerous album.
Background[]

Early Dangerous DAT
The track was recorded during sessions for the Dangerous album between 1989-1990. The title was included on the insert of a DAT featuring an early configuration of the album, which was found during the Brad Sundberg laptop theft. However, no information was given on the track.
According to a mjjcommunity.com user, when talking about the track with Bill Bottrell, he mentioned it to be a demo by Loren, meaning both Michael and Janet didn't record vocals for it.[1]