Of course it alters it.
A lie has to be about something, and that something is the facts in the case. But we now know that Fitzgerald never had the facts right. So of course Libby's story doesn't match up to Fitzgerald's version of the "facts", because Libby was telling the truth.
The lie in this case is the difference between what Libby had in his head, and what Libby said he had in his head.
The lie is not "the facts in this case" as to which reporter heard it first, etc. Those points are mere context to illuminate what Libby said he had in his head. The evidence about Libby contacting the CIA is to illuminate what Libby actually had in his head.