Any time you use the same uv's mirror'd on geometry you should make sure that the textures are flush, which might be one reason for your problem. Also what can be causing the problem is if you made the uv's then copied them to the other side vs just doing a straight projection so the uv's overlap seamlessly. You can see the distortion in the normal map where the lines are appearing so I dont think it's the uv's thats the problem but more so how your normal map was generated and transferred. Just out of curiosity did you use zbrush or maya to make the derformation/normals?
I was looking at your uv's and they arent in the same 0-1 space which might be the source of your problems. I'm unfamiliar with the plugin you used so i cant tell if maybe the settings weren't right there, but when i tried a quick render with extreme bump values the two sides were pushing in different directions which would explain why there is a line in the middle of your geometry especially if you used a low bump value.
ideally when you have the uv's mirrored you just want 1 set of uv's that you apply to 2 pieces of geometry. Not 2 sets of uv's assigned to 2 pieces of geometry, because that kinda of defeats the whole purpose or mirroring textures.