I can tell you that in my 25 years of concert going, I have seen one legit second encore. Van Halen, Molson Amphitheater, August 19 1995. VH thanked everyone after the regular tour encore, and walked off the stage. Lights went on, Sammy came back out as people were leaving and said...hey Edward, Edward, get back out here, let's do one more. Eddie was on the big TV screen and looked totally out of it and confused. Alex came out and started the drums for Panama. Check out the set lists for that tour. Legit. It would be nice to see more...but then everyone would want one...and so it would be planned.