Custom button on list view for sending document to multiple contacts

I originally created a custom list button with the wizard, but now I need to edit it and I'm not a programmer. The button ultimately sends an email to Accounting_Contact1__c. I just need it to ALSO send to Accounting_Contact_2__c.  Can someone tell me what this needs to change to?  

{!REQUIRESCRIPT("/soap/ajax/26.0/connection.js")}
{!REQUIRESCRIPT("/support/console/26.0/integration.js")}

var ids = {!GETRECORDIDS($ObjectType.Accounting_Record__c)};
if (!ids || ids.length < 1)
    alert("Please select at least one record.");
else
{
    var redirectUrl = "/apex/loop__masslooplus?&retURL=" + encodeURI(window.location.pathname+window.location.search);
    redirectUrl += "&recordIds="+ids.join(",");
    redirectUrl += "&sessionId={!$Api.Session_ID}";
    redirectUrl += "&contactField=Accounting_Contact1__c";
    window.location.href = redirectUrl;
}