DIVIDE PATH DIRECTION
If you divide a line the points created have an order. This can effect the behavior of objects connected to these points.
http://phil-osophyinbim.blogspot.com.au/2014/09/divide-path-direction.html
When you create a rectangle of lines (linking 4 points), Revit likes to draw the lines in a clockwise (or anti-clockwise) fashion. That means the two opposite lines are always drawn in opposite directions to each other; hence the divided paths are also opposite.