The Cmaj7(9,13) is a Cmaj7 chord with additional major 2nd and major 6th. Both are chord extensions: the 2nd does not replace the 3rd (sus2 chord), the 6th is not replacing the 7th. Therefore they must be notated as 9 and 13 in the chord symbol (not as sus2 and 6).
The Cmaj7(9,13) has the notes C (1), E (3), G (5), B (maj7), D (9) and A (13). The 5th can be omitted. On the guitar you will have a hard time to find a remaining string or finger to play it.
Theoretically you can always play a maj7(9,13) for a plain maj7 chord. For song accompaniment in general this chord has just too much color and doesn't sound straight enough. You may love it on the other hand when playing it in an arpeggiated way in some ballads.