ah my friend sry just didnt saw the normal map thing. we ll see these http://udn.epicgames.com/Three/LightMapUnwrapping.html http://stephenjameson.com/tutorials/lightmap-uvs-tutorial/ http://udn.epicgames.com/Three/LightMapUnwrapping.html
I think may b thats why UDN docs removed the article they had for ages there about how to mirror UVs, and replaced it with new info. Newayz have u tried baking normal map as a whole than breaking it apart in UV and in Photoshop. Yes the issue is from channel 0 which happens to b your Normal map, I had the exact same issue…