In this version, filmed before a live studio audience, Martha Raye1 plays Chaplin's role of Calvero, wearing a pot-bellied tux and, as an additional nod to the man she considered her idol, a Tramp mustache (Chaplin didn't have the Tramp mustache in Limelight). Keaton is wearing glasses and a tux but not the large mustache he wore in the film. Unlike the film version, this routine belongs to Keaton, who reworked the material from the original and restored some of the gags that had been cut from the final film, including his fall at the beginning and the bit where the piano lands on Martha's foot. We also see a variation on the high shirt collar business. When Martha's face is hidden behind the collar, Keaton pulls her head up by the hair "lengthening" her neck. Chaplin filmed a similar sequence but didn't use it (in the film he simply tears off the collar).
There has been a lot of talk over the years that Chaplin cut Keaton's best bits from the Limelight. Yes, he deleted a couple of good Keaton gags but it was for the purpose of the film. It would have made no sense for the Keaton character to upstage Calvero in this scene. The final music hall routine was supposed to belong to Calvero, it was his moment.
For a more in-depth comparison of the two routines, see Dan Kamin's essay, "The Three Ages Of Limelight" in Chaplin's Limelight & The Music Hall Tradition, edited by Frank Scheide and Hooman Mehran (McFarland, 2006).
1Raye appeared alongside Chaplin in Monsieur Verdoux (1947) as the indestructible "Annabella Bonheur."