I won’t adhere to the bug report format because the problem is not very specific. When two surfaces overlap, the renderer seems to work in an additive manner, so the overlapping parts are flashy (glowing corners, boo-hoo!).
I moved both pilasters by 0.1 voxel along z axis so ‘vertical’ surfaces don’t overlap but it is not possible with ‘horizontal’ ones. Is there a fix planned for that?
(the screenshot is obviously from the Archmod test)