Am I missing something. There are 4 power wires required, 2 positive pins 1 & 20 and 2 grounds pins 21 & 22. Are pins 1 & 20 connected to the same breaker (7.5A with no backup battery)?
There are two unterminated solid red primary power input wires (to re duce current loading in each wire—these are not for redundancy and both should be connected to the same power source) and two unterminated solid black primary ground wires.
I terminated both in a 18-22 AWG ring terminal.
I thaught that this would be preferrable than having each connected to their own power. In fact, if one of them should became loose, maybe current will burn the remaining wire. Joining both to the same connector will provide a working/no working installation. Provided that I have a backup battery, that was for me the best solution.
As Velocity pointed out, they do need to go to the same power source, and can just be hooked together at whatever point is easy.
Also, as Dick mentioned, it is to keep the load on the DSUB pins lower. They are spec'd for 5A, which is what we can draw on a really loaded system, so we decided to not push that spec.