Dual boot - cannot get to second grub menu (are my expectations wrong?)

I have two different distros installed. Os1 was installed by a gui installer first, with an efi partition and a system partition. Os2 is vanilla artix so I have set that up second using basestrap from the live environment. so now I have an efi partition containing: EFI/os1 EFI/os2 and then each os has its own partition with system files. I have run grub-install from os2 (was already done on os1) and grub-config from both oses with os-prober on and each now has a grub directory with their own config. Now at this point I am expecting to be able to go into my motherboard settings and select to either prioritize the os1 or os2 uefi and boot to their respective grub menus -which thanks to os prober I would expect to have options to go to either os. This is not what is happening. I can see an option for both in the motherboard boot menu but when selecting os2 it seems to just skip over it and revert to os1's grub menu (which does indeed have the option for both oses and I can boot into both from there). I simply want to know if what I am expecting (2 different grub menus) is the way things are supposed to work or have I misunderstood how grub and efi work together - Ive never bothered trying to run multiple grub menus before but have reason to now if possible.