Try:

Code:
~a::
IfWinActive, World of Warcraft
{
  ControlSend,, {a down}, ahk_id %wowid1%
  ControlSend,, {a down}, ahk_id %wowid2%
  Return
}

~a Up::
IfWinActive, World of Warcraft
{
  ControlSend,, {a up}, ahk_id %wowid1%
  ControlSend,, {a up}, ahk_id %wowid2%
  Return
}