I e-mailed them, asking if the two power leads were electrically the same, and was told this:
Positive power lead
Yes. They are both the same. We only use the Anode output (power lead at the monitor end) for a double din radio (reverse wire)
There's nothing "magic" inside the long cable. It's the same wire/signal at both ends. Their label "backing power supply anode output" is unnecessarily confusing.