I have following UV map!
Those islands are both same, but one of them is mirrored. I can mirror the one of the parts by selecting UVs -> Mirror -> X Axis (Ctrl-M)
however the hard part is they are not aligned and even rotating one does not make it exactly match the other one and it leaves stretched marks when rendering on one side of the model.
I have found this forum post about almost same issue (different blender version) which does not have a proper answer either.
I tried using snap with vertex but still no luck properly overlapping two islands.
Is there anyway to align islands to X, Y axis or other model?