Rare Joe Satriani live in the studio (Part 3 of 3 radio segments)

[brucecornell]

i dont know either what he means when he says he doubles up on the 3rd on the Gmaj 7th ? please help if anyone knows ? thanks :-)

[slimjoel14]

Please someone, when he says the chords for if i could fly, he says the first one is a Gmaj7, then he says he doubles up on the 3rd, what does that mean????