An inquest's heard that the MI6 spy whose body was found in a padlocked holdall in his bathtub sometimes went by a name other than Gareth Williams.
But his mystery second identity was not revealed as the coroner cut short the line of questioning to a friend of the 31-year-old.
Elizabeth Guthrie was asked by Mr Williams' family lawyer Anthony O'Toole whether the spy had told her he "sometimes used another name", to which she replied "yes".
She also revealed that Mr Williams had used a number of different phones to call her.
Mr Williams' body was found in his Pimlico flat in London in August 2010 but, 20 months on, the circumstances of his death remain unknown.
The inquest continues.