diff -uprb Thunar-1.4.0.orig/thunar/thunar-shortcuts-model.c Thunar-1.4.0/thunar/thunar-shortcuts-model.c
--- Thunar-1.4.0.orig/thunar/thunar-shortcuts-model.c	2012-11-03 07:42:39.000000000 +0200
+++ Thunar-1.4.0/thunar/thunar-shortcuts-model.c	2012-11-03 08:13:25.000000000 +0200
@@ -1221,11 +1221,25 @@ thunar_shortcuts_model_volume_added (GVo
                                      GVolume              *volume,
                                      ThunarShortcutsModel *model)
 {
+  GList *lp;
+  gint  idx;
+
   _thunar_return_if_fail (G_IS_VOLUME_MONITOR (volume_monitor));
   _thunar_return_if_fail (model->volume_monitor == volume_monitor);
   _thunar_return_if_fail (G_IS_VOLUME (volume));
   _thunar_return_if_fail (THUNAR_IS_SHORTCUTS_MODEL (model));
 
+  /* check that the volume is not in the internal list already */
+  if (g_list_find (model->hidden_volumes, volume) != NULL)
+    return;
+
+  /* nor in the list of visible volumes */
+  for (idx = 0, lp = model->shortcuts; lp != NULL; ++idx, lp = lp->next)
+    {
+      if (THUNAR_SHORTCUT (lp->data)->volume == volume)
+        return;
+    }
+
   /* place the volume on the hidden list */
   model->hidden_volumes = g_list_prepend (model->hidden_volumes, g_object_ref (volume));
 
diff -uprb Thunar-1.4.0.orig/thunar/thunar-tree-model.c Thunar-1.4.0/thunar/thunar-tree-model.c
--- Thunar-1.4.0.orig/thunar/thunar-tree-model.c	2012-11-03 07:42:39.000000000 +0200
+++ Thunar-1.4.0/thunar/thunar-tree-model.c	2012-11-03 08:09:36.000000000 +0200
@@ -1127,11 +1127,26 @@ thunar_tree_model_volume_added (GVolumeM
                                 GVolume                *volume,
                                 ThunarTreeModel        *model)
 {
+  ThunarTreeModelItem *item = NULL;
+  GNode               *node;
+
   _thunar_return_if_fail (G_IS_VOLUME_MONITOR (volume_monitor));
   _thunar_return_if_fail (model->volume_monitor == volume_monitor);
   _thunar_return_if_fail (G_IS_VOLUME (volume));
   _thunar_return_if_fail (THUNAR_IS_TREE_MODEL (model));
 
+  /* check that the volume is not in the internal list already */
+  if (g_list_find (model->hidden_volumes, volume) != NULL)
+    return;
+
+  /* nor in the list of visible volumes */
+  for (node = model->root->children; node != NULL; node = node->next)
+    {
+      item = THUNAR_TREE_MODEL_ITEM (node->data);
+      if (item->volume == volume)
+        return;
+    }
+
   /* place the volume on the hidden list */
   model->hidden_volumes = g_list_prepend (model->hidden_volumes, g_object_ref (volume));