Hi,
I put a texture on a Plane Mesh whith UV mapping, I export it with the three.js exporter, I import the result in the three.js editor and I see the texture mirrored on X and Y.
There is something special to set in blender or there is a problem with the exporter ?
I tried with blender 2.78c and 2.76b with the last version of the three.js exporter.