PVS-Studio warning V581 for Asterisk

static void sip_threadinfo_destructor(void *obj)
{
  struct sip_threadinfo *th = obj;
  struct tcptls_packet *packet;

  if (th->alert_pipe[1] > -1) {            //<==
    close(th->alert_pipe[0]);
  }
  if (th->alert_pipe[1] > -1) {
    close(th->alert_pipe[1]);
  }
  th->alert_pipe[0] = th->alert_pipe[1] = -1;
  ....
}

This suspicious code was found in Asterisk project by PVS-Studio static code analyzer.
Warning message is:
V581 The conditional expressions of the 'if' operators situated alongside each other are identical. Check lines: 2513, 2516. chan_sip.c 2516

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/