CWS Vandy/Texas

[Texas Aggie]

In like the 5th or 6th inning of the Sat. night game between Vandy and Texas, Vandy attempted a suicide squeeze but the pitch was nowhere near bunt-able and the player running home from 3rd was caught in no man's land. But the runner from 2nd was now at third. The catcher chased R3 back to the bag but didn't tag him until he was on the back, causing U3 to call that runner safe. Catcher now tries to tag R2, which he does (U3 calls him out) but the problem was that between the first and second tag by the catcher, R3 left the base. It happened very fast and I know U3 didn't see that, but I ran it back several times and even at regular speed, it was clear that R3 did leave prior to the second tag. Anyway, R3 was then tagged out and U3 ruled both were out. Only R2 stayed to argue and no one seemed to make a big deal out of it.

I don't work baseball, but was wondering: with 2 runners on the same base, does the fielder have to tag the runner who doesn't belong there? Did the tag on R2 become meaningless when R3 left the base?

R3 is definitely out, but I'm wondering if R2 should have been as well. If a tag is not necessary, then it was correct. If one was, then I wonder, but I don't know the NCAA rule.