Script hanging?

I've added a listen to a script to take verbal commands. However it at times processes the command several times over and, in the case of the commands which receive an audible response from the script, can spam any in the area. I originally thought this to be caused by lag, however it happens in empty sims. In fact, I just tested it in a sim by myself with a time dilation of 1 and Sim FPS of 800+ and it repeated nine times. Any theories as to the cause or possible solutions?

From the excellent LSL Wiki:

"If you call llListen again with the identical criteria, you create a duplicate filter and your listen() event handler will be called multiple times."

And if you have an object that calls llListen() in state_entry() it will create a duplicate filter every time you pull if out of inventory unless you remove it or otherwise keep a duplicate from being made, e.g.

integer listenHandle = -1;

default {
    state_entry() {
        if(listenHandle == -1)
           listenHandle = llListen(...);
     }
}

Worked like a charm. Thanks!