Thank you for your message.
The S12II-520, as you can see on our website (specification tab), got 2 rails +12V. The PSU got all the protection to avoid any problem.
If you have any other question, you can contact us anytime.
Fire hazard? lol Maybe with the lowest-quality power supplies plugged into the worst power lines.
Multiple +12v rails was a thing for a short while. The vast majority of PSUs are back to a single rail and have been for years. They use the +12v rail with DC-to-DC conversion for the +3.3v and +5v rails.
There is no more fire hazard with these than with a radio or television or lamp or phone charger.