Does you object have a lightmap? If not, the engine will try to bake lighting into the object's vertices. The verts will probably bake black since they are so close (or in) to the wall.
usually only lightmaps have a different UV channel but everything else is usually on UVchannel #1 (difuse, normal, spec,...). SO that would not make sense
add a skylight and a direct light and bake a lightmap to say uvchannel 2. would look better . render the pics with catmull.rom, makes the render look sharper