When you have a line of repeaters with one of the repeaters in the middle powered, then load (with structure blocks) a line of unpowered repeaters in the same position as the original line, some repeaters in the new line become powered. It's like the previous repeater has the ability to power some loaded repeaters. (when you load the structure block, the original powered repeater becomes unpowered)

What should happen is that the loaded repeater line should be completely unpowered.