Event Listener Fires Twice

[Claus Mygind]

I am baffled as to why an event listener is firing twice on me.

I have two apps that share the same piece of code. Each app has two search buttons, So a total of 4 search buttons. Each executing the same code with different parameters. Of the 4 buttons only one fails by firing twice on a single click.

Here are the buttons as coded in the two apps:

from App1:
<input 
    type="button"         
    id  ="sbReqClient"         
    value="Change Client"         
    class="InputText"
    tabindex="-1" 
/>
<input 
    type="button"         
    id  ="sbComClient"         
    value="Change Client"         
    class="InputText"
    tabindex="-1" 
/>
 
from App2:
<input 
    type="button"         
    id  ="sbReqClient"         
    value="Change Client"         
    class="InputText"
    tabindex="-1" 
/>
 This button when clicked fires twice
<input 
    type="button"         
    id  ="sbComClient"         
    value="Change Client"         
    class="InputText"
    tabindex="-1" 
/>
 

Each button is assigned an event listener like so. I copied this code from the one app to the other app, so the code is identical.

 
 For button 2 in app 2 this eventlistener fires twice.
    g.sbComClient = document.getElementById('sbComClient');
    if (g.sbComClient.addEventListener)
    {
        g.sbComClient.addEventListener("mousedown",
                                        function(evt)
                                        {
                                            smallSearch('Client Id','10','8','CLIENT','ID','ComClient','Yes','startSmallSearch');
                                        },
                                    false)
    }
 
    g.sbReqClient = document.getElementById('sbReqClient');
    if (g.sbReqClient.addEventListener)
    {
        g.sbReqClient.addEventListener("mousedown",
                                        function(evt)
                                        {
                                            smallSearch('Client Id','10','8','CLIENT','ID','ReqClient','Yes','startSmallSearch');
                                        },
                                    false)
    }
 
 Here is code from app1 which fires properly so you can see all the code involved
    g.sbComClient = document.getElementById('sbComClient');
    if (g.sbComClient.addEventListener)
    {
        g.sbComClient.addEventListener("mousedown",
                                        function(evt)
                                        {
                                            smallSearch('Client Id','10','8','CLIENT','ID','ComClient','Yes','startSmallSearch');
                                        },
                                    false)
    }
 
    g.sbReqClient = document.getElementById('sbReqClient');
    if (g.sbReqClient.addEventListener)
    {
        g.sbReqClient.addEventListener("mousedown",
                                        function(evt)
                                        {
                                            smallSearch('Client Id','10','8','CLIENT','ID','ReqClient','Yes','startSmallSearch');
                                        },
                                    false)
    }
 
 
 

From this point forward all 4 buttons run the exact same code from linked files.

Where should I be looking for the cause of the problem?
What are some possible explanations for multiple firings? I understand double click and that is not the problem, I have checked that.

[Claus Mygind]

I found the error. The one button firing twice had the event listener defined twice. Too much copying of the code. Well there goes 2 hours of my life that could have been spent better.