this is my current decision, but I'm still missing some information, that I might get on Monday.
DualBIOS unfortunately has nothing to do with disabling UEFI/Secure boot.
"GIGABYTE UEFI DualBIOS™
GIGABYTE motherboards feature GIGABYTE DualBIOS™, an exclusive technology from GIGABYTE that protects arguably one of your PC's most crucial components, the BIOS. GIGABYTE DualBIOS™ means that your motherboard has both a 'Main BIOS' and a 'Backup BIOS', making users protected from BIOS failure due to virus attack, hardware malfunction, improper OC settings or power failure during the update process."