The cable is only rated for so much power, which could be too much for double 8 pins. Having two operated cables ensures it can handle the load.
I personally used a single cable that carried double 8 pin. At some point, I had issues with my system crashing under GPU load. After investigating, I found that the GPU wasn’t getting the power it needed from the PSU. Looking at the cable, it had started to melt the plastic with the connector in the PSU. I replaced the cable and it was fine, but now I only use one cable per 8 pin connector.
I feel the someway about people who say “I’m moving to Linux after W10 support ends”.
I think it takes one of two things for people to move.
In my case, I swapped back 3 years ago when ads appeared in explorer for a preview version. In combination with the work the community had done for Valve to consider the steam deck worth selling with Linux, I was confident enough that I could have a good enough experience with Linux.