Hi, i have a problem with painting on mirrored uv’s because it creates a small seam.I attached a video with this behaviour and i should also mention that it does this where it finds a mirror seam, every other non mirror seam is fine.I would be thankful is someone could find a fix for this problem.
http://www.youtube.com/watch?v=65pDya1wJps
You may get a better result if you turn on Airbrush in the paint Stroke panel or paint along the seams in the UV/Image editor window rather than in the 3dview
I think i was too anal about it, actually separating the mirrored parts as objects works fine.