Why do you need to strike the testimony1? in fact, why do you even want to do that? A good lawyer would want to keep that testimony, as an indicator how bad the testimony was. As an indicator that the prosecution did not beyond a reasonable doubt prove their case. Let's ask Devin how to deal with a witness that you demolish so utterly that all he can say that he saw something but it's utterly unreliable? No wait, let's watch a movie together, where we do that with three witnesses! Yes, let's lawyer My cousin Vinnie, because in that regard, the movie is accurate to some degree. Have the witness agree with statements that dismember his credibility. Remember, the standard in a criminal case is beyond a reasonable doubt, as in, that nobody could reasonably believe the allegation was wrong. It's not by the preponderance of the evidence, as in a civil case, which means "more likely than not."
L: You were just ready to eat, and you heard a gunshot. That's right,
I'm sorry. So, obviously, it takes you five minutes to make breakfast.
W: That's right.
L: Right, so you knew that. Uh, do you remember what you had?
W: Eggs and grits. [...]
L: Instant grits?
W: No self-respectin' Southerner uses instant grits. I take pride in
L: So, Mr. Tipton, how could it take you five minutes to cook your
grits, when it takes the entire grit-eating world twenty minutes?
Is this witness believable? Can you believe the witness that had to see through dirt, a screen, and 7 bushes?! Can you believe the prosecutor's expert if all he can tell it was the most popular tire on the most popular car?
No? So if you can't believe these witnesses at all, how can there not be reasonable doubt?!
Ok, seriously, there are reasons when you want testimony gone. But in those cases, the testimony shouldn't have been in in the first place, because it is not admissable as evidence:
it was improperly obtained, it is prejudicial (the prejudicial value outweighs the probative value), it is hearsay, it is not relevant to the case, etc.
Conflicting statements only could become inadmissible if they make the whole witness irrelevant (not relevant) or everything is hearsay, but the fact of exposing the hearsay also points out very nicely that the persecution has a very very weak case. Also, the hearsay and opinion ban has holes, especially for experts.