That is not the only time he testified.
26. As part of the criminal investigation, LIBBY was interviewed by Special Agents of the FBI on or about October 14 and November 26, 2003, each time in the presence of his counsel. During these interviews, LIBBY stated to FBI Special Agents that: ...
That is not "testimony", insofar as Libby is not under oath, and has no obligation to assist the FBI.
Read the indictment, hot shot. He was indicted for his testimony in March 2004:
"31. In or about March 2004, in the District of Columbia,
I. LEWIS LIBBY, also known as "SCOOTER LIBBY,"
defendant herein, did knowingly and corruptly endeavor to influence, obstruct and impede the due administration of justice, namely proceedings before Grand Jury 03-3, by misleading and deceiving the grand jury as to when, and the manner and means by which, LIBBY acquired and subsequently disclosed to the media information concerning the employment of Valerie Wilson by the CIA."