The answer is "it depends on what you mean" - All (or rather, nearly all) Gigabyte motherboards that I am aware of in the X570/B450 lines have a what you'd call "Dual-BIOS" - it basically means that 2 BIOS revisions are stored in EPROMs on the motherboard, and in the event one fails, that failure is detected and then the system is rebooted using the other "backup" BIOS automatically. This can operate in a few unexpected ways, but generally helps you avoid your machine being bricked in the event something happens. At least, that's the whole intent.

This is an old link, but it explains the feature & process (on a general level, not for specific boards): https://www.gigabyte.com/microsite/55/tech_081226_dualbios.htm

However, if you're referring to a Dual-BIOS motherboard that supports "Single Mode" BIOS operation (i.e., the ability to store 2 different BIOS versions on your board and switch back and forth between them by switching a physical dip switch on the motherboard itself, but otherwise keeping them completely separate and giving the ability to disable "auto-failover" in favor of failing over manually), then I believe this is only offered in the AORUS MASTER (and higher) boards.

Hopefully this helps - I wanted to spell that out in case you meant one thing or the other. Personally, I wanted the physical dip switch and the ability to control the failover, so I went with an X570 AORUS MASTER board in my own build. I'm reasonably sure the B450's would be something similar.

If all else fails, look at the pictures of the motherboard near the ATX connector block, you should see 2 dip switches there on boards that support the "Single Mode" feature.