You can tell HotkeyNet to send to the foreground window or to windows that you identify by their names. That's all the choices.

If you're in a hackerish mood and want to try something tricky, maybe the following will work. Make a hotkey that renames each WoW as it executes and then renames them back when it's finished. Something like this:

Code:
<Hotkey LButton>  // YOU PROBABLY WANT MORE KEYS IN THE TRIGGER
                    // SO IT DOESN'T FIRE ALL THE TIME

   <SendPC ........>

      <RenameWin World WoW1>
      <SendWinM WoW1>
      <ClickMouse LButton>

      <RenameWin World WoW2>
      <SendWinM WoW2>
      <ClickMouse LButton>

      <RenameWin World WoW3>
      <SendWinM WoW3>
      <ClickMouse LButton>

      <RenameWin WoW1 "World of Warcraft">
      <RenameWin WoW2 "World of Warcraft">
      <RenameWin WoW3 "World of Warcraft">