Second perfect is the same as perfect, but the way the conjugation is formed is different.
Example
ἀκηκόαμεν γὰρ αὐτοῦ λέγοντος ὅτι Ἰησοῦς ὁ Ναζωραῖος οὗτος καταλύσει τὸν τόπον τοῦτον For we have heard him say, that this Jesus of Nazareth shall destroy this place