I've seen multiple tornadoes simultaneously on a few occasions:
May 3, 1999 - Near Minco, OK, we nearly got squashed by a new tornado just southwest of us as it developed from the new meso; we'd been focused on the original tornado due west of us. This incident was how I learned about cyclic storms and occlusions, lol. Who needs the classroom?
May 3, 2003 - South of Haskell, TX, we watched a multiple vortex dust whirl tornado form. A few minutes later, a dust whirl tornado formed on the forward flank, giving us two tornadoes side by side. As this was ongoing, a third, white cone tornado developed behind the original tornado (to the west), giving us three at once for about 30 seconds from the same storm.
March 27, 2004 - Though only one touched down, we saw two funnels develop side by side from a storm right before dusk, near Okarche, OK. The larger of the two briefly touched down, becoming a tornado, but the smaller funnel persisted longer. We were just taping the storm and weren't even expecting it, but when it happened we were watching the right spot :wink:
May 29, 2004 - Again right around dusk, near Argonia, KS, we witnessed two tornadoes at once. We'd approached the storm from the west, and rain/hail had blocked our view of the Argonia wedge as it moved north of 160.....we literally drove right behind it and never actually saw it while it was mature. About ten minutes later, we'd stopped and were taping the Conway Springs wedge. As this tornado was maxing out (just NNE of us), the rain/hail cleared northwest of us and the roping Argonia tornado came into full view. Pretty spectacular stuff 8)