latimesblogs.latimes.com — Last weekend as the first of two identical weekends of the Coachella Valley Music and Arts Festival drew to a close, Dr. Dre and Snoop Dogg unveiled a shocking surprise when the pair reincarnated slain West Coast superstar Tupac Shakur onstage in a hologram-like image that rapped and danced along with the two very alive heavyweights.