Case Play 2015-06, Running Out of a Rundown

When the Cubs caught Mets baserunner R3 Ruben Tejada in a rundown between third and home on a botched suicide squeeze in the 8th inning of Wednesday's game, Chicago catcher Miguel Montero decided to run Tejada back to third base, noticing that trailing Mets baserunner R2 Daniel Murphy had run in behind Tejada and was standing on third base.

"This is like Final Jeopardy! on the umpire exam....Time to go digging for the ol' rule book."

U3 Guccione halts play at third base.

Instead of giving himself up, Tejada ran through third base while F2 Montero tagged R2 Murphy, standing on third base, before subsequently applying the tag to R3 Tejada, who was still standing up the left field line, several feet behind (and not touching) third base. 3B Umpire Chris Guccione initially called both runners out before quickly reversing course and asking Murphy to remain on third base while the umpires convened. After consultation with umpires Clint Fagan, Cory Blaser, and acting crew chief Laz Diaz, Guccione ruled R3 Tejada out and R2 Murphy safe at third base.

Replays indicate that when F2 Montero tagged R2 Murphy, R3 Tejada was not in contact with third base (having already ran past it).
Video: Darrell Ceciliani can't get the bunt down, leading to Mets mayhem at third base (CHC)

Case Play Question, 2015-06: What is the proper call here? Rule 7.03(a) [OBR 2015 Rule 5.06(a)(2)] states that, "Two runners may not occupy a base, but if, while the ball is alive, two runners are touching a base, the following runner shall be out when tagged and the preceding runner is entitled to the base" (unless it is a force play), but what happens when said preceding runner attempts to retreat to his base and overruns it while the trail runner is in contact?

Hint: Which came first, the chicken or the egg?