diff --git a/sat/plugins/plugin_xep_0334.py b/sat/plugins/plugin_xep_0334.py
index d1c3416f..571cdf55 100644
--- a/sat/plugins/plugin_xep_0334.py
+++ b/sat/plugins/plugin_xep_0334.py
@@ -92,7 +92,10 @@ class XEP_0334(object):
         @param hints: hints to add
         """
         for hint in hints:
-            message_elt.addElement((NS_HINTS, hint))
+            if not list(message_elt.elements(NS_HINTS, hint)):
+                message_elt.addElement((NS_HINTS, hint))
+            else:
+                log.debug('Not adding {hint!r} hint: it is already present in <message>')
 
     def _sendPostXmlTreatment(self, mess_data):
         if "hints" in mess_data: