Text (CH+errata): 1/3. ; {Tap}: ~this~ deals 1 damage to target creature or player and 1 damage to target creature or player of an opponent's choice. [Oracle 1999/09/03]
Both targets are chosen on announcement, but you choose your target before the opponent chooses. [WotC Rules Team 1995/08/17]
The two targets must be different. [D'Angelo 2001/07/14]
It does not target the opponent, but you still choose an opponent. [WotC Rules Team 1998/02/01]
If either target becomes invalid, the other one is still affected. [Aahz 1995/05/23]
In multiplayer games you can choose a different opposing player each time it is used. [Duelist Magazine #4, Page 64] You also don't have to choose the same player that you targeted with the effect (or whose creature you targeted).
Extended tournaments (see Rule 913) have banned this card since 1999/10/01.
Note - This card was of creature type "Witch" and not "Human Wizard" until Oracle 2007/09/01.