PVS-Studio warning V501 for Firefox

float
PannerNode::ComputeDopplerShift()
{
  ....
  double scaledSpeedOfSound = listener->DopplerFactor() /
                              listener->DopplerFactor();
  ....
}

This suspicious code was found in Firefox project by PVS-Studio static code analyzer.
Warning message is:
V501 There are identical sub-expressions 'listener->DopplerFactor()' to the left and to the right of the '/' operator. pannernode.cpp 529

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/