PVS-Studio warning V501 for VTK

static int
xmlSchemaCheckCOSNSSubset(xmlSchemaWildcardPtr sub,
                          xmlSchemaWildcardPtr super)
{
  ...
  if ((sub->negNsSet != NULL) &&
      (super->negNsSet != NULL) &&
      (sub->negNsSet->value == sub->negNsSet->value))
      return (0);
  ...
}

This is what should have been written here: (sub->negNsSet->value == super->negNsSet->value).

This suspicious code was found in VTK project by PVS-Studio static code analyzer.
Warning message is:
V501 There are identical sub-expressions 'sub->negNsSet->value' to the left and to the right of the '==' operator. vtklibxml2 xmlschemas.c 13873

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/