The double was allegedly used at Londonís O2 Arena alongside TV host Dermot OíLeary in 2009, the Daily Star reported.
The family also suspects that the clips showing the `Thriller` star rehearsing, also used in a movie later, featured a double.
The allegations were made by Jacksonís children Paris and Prince and their grandmother Katherine in a 26-billion-pound claim.
They suggested that the singerís tour bosses hired a body double, as Jackson was not fit enough.
The family also claimed that the promoters AEG `mishandled` the star, who died at the age of 50, three weeks before the tour.
They also accused that the firm was negligent in hiring disgraced doctor Conrad Murray, who gave the star a fatal dose of anesthetic.
Bianca Cobb, a body language expert, said that, in his opinion, the man in the clips wasnít Michael Jackson.
He added that the walk in the clip was cockier, had more bounce than MJís typical style and that he tended to walk with his head down.
The Jacksons have appealed for the double to come forward and give evidence at the Los Angeles court.
However, the tour promoters have denied the claim and Sony, who released the movie showing Jackson rehearsing, said that every frame was undeniably the legendary musician.
A family source revealed that the starís family has hired detectives to track down the fake MJ.