Board Thread:Questions and Answers/@comment-116.65.70.72-20130727121600/@comment-5527544-20130727145935

The two lives were for Zoffy and Ultraman, you could assume Zoffy was just testing Ultraman to see how much he had grown. Since he had two lives there was never a concern about Hayata's life since the battle was over, so it stands to reason that he just wanted to see first hand how much Ultraman had grown as a person thanks to the humans.