python - Dajaxice callback function called twice -

i'm using django-dajaxice-ng package (django-dajaxice fork django 1.5 , above, since use django 1.5.4), , have strange issue.
callback function called twice or more.
simple usage:

... {% load dajaxice_templatetags %} ... {% dajaxice_js_import %}  <script>      function update_chat(data) {         messages = eval(data.messages);         howmany=messages.length;         if (howmany>0)             console.log('called');         (i=0;i<howmany;i++) {             m=messages[i];             console.log(m.msg,m.sent);         };     }      setinterval(function() {             dajaxice.myapp.receivechat(update_chat,{'userid': {{otheruser.id}} });     },2000);   </script> 

and in myapp/ajax.py:

def receivechat(request,userid):     # find new messages userid , mark them read.     return json.dumps({'messages':serialized_messages}) 

here's console log:

called "message" "16:09:28" called "message" "16:09:28"  

as can see, (very often, actually) update_chat triggered 2 or 3 times.
i'm 100% sure that:

• the ajax function receivechat called once
• the message shown twice stored once.

i define serialized_messages = json.dumps(messages), being messages list of dicts.
result this:

'[{"msg": "message", "sent": "16:09:28"}]' 

in case there's 1 message, works more one.

i had double serialization (the other one's in return) because apparently dajaxice accept dict admitted return values.

anyone got behavior? clue?

edit i'm using neo4django uses neo4j-rest-client, have .save() on model, , notice save got problem, maybe because of http request?

edit 2 it's not dajaxice issue, switching ajax $.get() gives same results, can't figure out. seems not browsers doing it, sure chrome does.