Here the typesetter for the 1849 LDS edition added the perfect auxiliary had. He was probably influenced by the use of had in the preceding clause (“and Coriantumr had taken all the people with him”). The subsequent LDS edition (in 1852) removed the intrusive had. Note that had was not inserted at the end of the verse (“whither he fled”).
Summary: Maintain in Ether 14:15 the lack of the perfect had before fled for both instances of that verb in the verse.