Help please :)

//i want an object to rez when it is triggered but it make 2 rez instead of 1 of the object i want it to rez

integer listenHandle_a;


default
{
    on_rez(integer start_param)
    {


        listenHandle_a = llListen(12, "", NULL_KEY, "");

    }

    listen(integer number, string name, key id, string message)
    {

        if(message=="Stop Spin"){
              llRezObject("~Exterior #1", llGetPos() + <0.0,0.0,2.0>, <0.0,0.0,0.0>, <0.0,0.0,0.0,1.0>, 0);

    }
    }
}