add: if(menu.getElementsByAttribute("label", element.title).length > 0) return; 
context: function smLinkAdded(evt){  var element = evt.originalTarget;  if (element.ownerDocument != getBrowser().contentDocument ||      !linkToolbarUI.isLinkToolbarEnabled() ||      !element instanceof Components.interfaces.nsIDOMHTMLLinkElement ||      !element.href || (!element.rel && !element.rev))    return;  if (element.rel.indexOf("stylesheet") < 0 || element.title=='')    return;  var menu = document.getElementById("stylesheets-menu-popup");  var item = document.createElement("menuitem");  item.setAttribute("label",element.title);  item.setAttribute("type","radio");  item.setAttribute("oncommand", "stylesheetSwitchAll(window._content,'"+element.title+"')");  menu.appendChild(item);  menu.parentNode.removeAttribute("disabled");}
meta: 1647	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/1647/cfbd708ab7252f123a41cfb370e22669e22a8443/styleLinkToolbarOverlay.js/clean/src/tbstyle/styleLinkToolbarOverlay.js