'THIS IS IT' CD WON'T INCLUDE REHEARSALS: Sony is calling two-disc set a 'companion album.'

       Instead, the first disc will contain original album masters of the late singer's biggest hits, arranged in the same order as they appear onscreen, while disc two will include previously unreleased versions of Jackson songs, plus the heretofore-unheard "Planet Earth," termed a "spoken word poem."       

       The disc will be released internationally Oct. 26 and domestically on Oct. 27 by Sony Music's Columbia/Epic Label Group. It'll be preceded on Oct. 12 by the release of a new Jackson single, also titled "This Is It."      

       Two versions of the single will be included on the album, with Jackson's brothers supplying backing vocals for the newer track.