--- a/toolkit/modules/PopupNotifications.jsm
+++ b/toolkit/modules/PopupNotifications.jsm
@@ -725,16 +725,20 @@ PopupNotifications.prototype = {
       popupnotification.hidden = false;
     }, this);
   },
 
   _showPanel: function PopupNotifications_showPanel(notificationsToShow, anchorElement) {
     this.panel.hidden = false;
 
     notificationsToShow = notificationsToShow.filter(n => {
+      if (anchorElement != n.anchorElement) {
+        return false;
+      }
+
       let dismiss = this._fireCallback(n, NOTIFICATION_EVENT_SHOWING);
       if (dismiss)
         n.dismissed = true;
       return !dismiss;
     });
     if (!notificationsToShow.length)
       return;