Presuming the committee calls the witness back and says “Explain yourself.”
The problem, Mr. Chairman, that you have when you have two different versions and someone says to them, you said x here and you said y here, which is the truth? This is a serious problem in the whole area of perjury. Logically they both can't be true. The critical thing is not that one of them is untrue, but that the testimony given here was untrue.
Now, how are you going to prove the testimony over there was true and untrue here, except by saying, it was given at a judicial inquiry; therefore, it must be true. If you're prepared to say that, then you win; but I don't know that you can necessarily say that. And that's the problem with perjury: where is the truth?