[SR-Users] duplicate information in siptrace table

[Fred]

Hello,

I use Kamailio 4.1.3 with siptrace module. In the sip_trace table I see 
duplicate information, one line with empty and one line with filled 
traced_user column.
The empty lines are useless for me, I would like only entries with 
traced_user information.

Here the siptrace part of kamailio.cfg:

#### Parameters for Siptrace module
modparam("siptrace", "db_url", DBURL)
modparam("siptrace", "trace_on", 1)
modparam("siptrace", "trace_flag", 22)
modparam("siptrace", "trace_sl_acks", 0)
modparam("siptrace", "traced_user_avp", "$avp(s:user)")
modparam("siptrace", "trace_delayed", 0)

###### SIP Trace Config in main route
    if (!is_method("OPTIONS")) {
       if (!ds_is_from_list("2")) {
          $avp(s:user) = $fU;
       } else {
          $avp(s:user) = $rU;
       };
       if (is_avp_set("$avp(s:user)")){
          sip_trace();
          #setflag(22);
       };
    };

Has anyone a tip for me how I can get rid of the empty traced_user lines?

Regards
Fred