PVS-Studio warning V523 for UCSniff

int openreceivehandler(....)
{
  ...
 int return_rtp = check_rtp_entry(ip);
 if (return_rtp < 0) {
   int return_value = populate_rtp_struct(return_rtp, ip,
                                          passthrupartyid,
                                          rtpport);
   if(return_value == -1) {
     return NULL;
   }
 } else {
   int return_value = populate_rtp_struct(return_rtp, ip,
                                          passthrupartyid,
                                          rtpport);
   if (return_value == -1) {
     return NULL;
   }
 }
  ...
}

This suspicious code was found in UCSniff project by PVS-Studio static code analyzer.
Warning message is:
V523 The 'then' statement is equivalent to the 'else' statement.  ec_sccp.c 3216

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