Actually now looking at the Chronicles pic again, I see what you're talking about. And what I just proposed couldn't have been the way they attached the piece--bending the wires out and into the clamp. It definitely looks like the wire is coming out of the clamp and then bends around and rests in a groove between the ridges on the booster.
However, maybe this is why there appears to have been two holes drilled. Maybe the propmaker just drilled holes in the clamp for the wires to go through, but then when he put the clamp onto the booster he saw that the ring of holes underneath blocked the holes for the wires that he just drilled. So he drilled new holes right next to them, and stuck the wires through those, leaving the extra piece screwed all the way in or at least close to it. What do you think?