Feud? What feud? While NBC is reportedly poised to replace longtime Tonight Show host Jay Leno with Jimmy Fallon, there doesn't seem to be any bad blood between the pair -- a fact they made abundantly clear when they performed a duet together Monday night.Late Night have collaborated. Watch the full clip below. What do you think of the bit? Report: Seth Meyers to replace Jimmy FallonEarlier in the night, Leno continued to take jabs at NBC during his opening monologue. Leno said he and the network "have reached a peaceful, amicable agreement that will be beneficial to both sides... April Fools! It will never happen."