1- Yep, you have at least two solution : change V mapping values to avoid 0.0 or 1.0 (use 0.01 or 0.99) as said Turbo Lover or use a pure transparent line at the bottom of your tga file as said TTM.
2- Check Normals because it comes from there. check that this plate has normals facing the same way than other plates. If so you might need to average normals for each 4 vertice with the same vertice of neighbour faces.
basically, you can add normals coordinates (X1+X2, Y1+Y2 and Z1+Z2) and divide by 2 to get final unique normal to apply to vertice of this plate and also to vertice of neighbour face. (I hope the above is understandable, I'm not sure it is).
Another try to explain:
Take one vertice of the plate, if it's normal is different than the same vertice belonging to neighbour face, then you need to average both normals coordinates and set the new average values to both vertice. And this for all 4 vertice.