PVS-Studio warning V501 for VTK

void vtkImageStencilRaster::PrepareForNewData(....)
{
  ...
  if (allocateExtent &&
      allocateExtent[1] >= allocateExtent[1])
  ...
}

This suspicious code was found in VTK project by PVS-Studio static code analyzer.
Warning message is:
V501 There are identical sub-expressions to the left and to the right of the '>=' operator: allocateExtent[1] >= allocateExtent[1] vtkImaging vtkimagestencildata.cxx 1178

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/