Comment 2 for bug 320646

First I confirm this issue.
I played a litte bit with your drawing. Your circles are geometrically not 100% identical, one is open, they have different skew values, the points are not on the same coordinates, etc.
All of this differences are in the 4th or so digit. So I guess there is an numerical issue in the path representation during the conversation to cairo that leads to this visible differences.
What is the numerical representation in the Lib2geom (inkscape-cairo.cpp) ?
Adib.