User blog comment:Thailog/Ep. 204 "Salvage" discussion/@comment-5118536-20120520152549

I think Gaurdian found out he was a clone in "Auld Acquaintance" at the end sequence at Cadmus you see Ra's taking inventory after what seems like a quick but brutal battle ( Dr. spence knocked out G-nomes all over the floor) then there is Gaurdian standing frozen with the same look Connor had when "Red Son" shut him down. So he would have found out through similarities between Connor, Red Arrow, and himself.