The show gives you the impression that he really did die at the end of "Seconds." Before the ceiling collapsed, he closed his eyes and fell back as if he was dead. Then the whole ceiling collapsed on top of him and the Lois clone. He never appeared again in person, only as a recording during the Lex Jr. arc in Season 4 when Lex Jr. was trying to repair a tape which revealed Clark's identity as Superman. Apparently in the very short time between the the Lois clone telling him Clark's secret and the time Luthor kidnapped Martha, he had the time to make the tape.
Here's a question I've been wondering about. Many fanfics used the name Clois for the Lois clone. Who coined that name first? It wasn't in the show so I'm assuming a fanfic author came up with the name.
