PVS-Studio warning V501 for QT

static ShiftResult shift(....)
{
  ...
  qreal l = (orig->x1 - orig->x2)*(orig->x1 - orig->x2) +
            (orig->y1 - orig->y2)*(orig->y1 - orig->y1) *
            (orig->x3 - orig->x4)*(orig->x3 - orig->x4) +
            (orig->y3 - orig->y4)*(orig->y3 - orig->y4);
  ...
}

Seems like it should be "orig->y1 - orig->y2" instead of "orig->y1 - orig->y1".

This suspicious code was found in QT 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: orig->y1 - orig->y1 QtGui qbezier.cpp 329

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/