Revealing the Alias of another Player

(a) The only valid reason for using a second username (alias) is to experiment with a different style of bidding or play or perhaps just to play a relaxing game without worrying about the pressure of gaining or losing points.
(b) The only valid reason for revealing another player's alias is if there is reason to believe that the person is using the alias to sabotage another player's game.
(c) If a player is not happy about his/her alias being exposed it is a simple matter to establish a new alias.

* Unfortunately it is often impossible to distinguish (a) from (b) so there can be no prohibition against revealing another player's alias.
i.e. At his/her own discretion a player is allowed to reveal another player's identity. Keep in mind that the identification could be erroneous.