Has anyone try running two ESXi booting from a 2xUSB flash on a single hardward box? Someone has just ask me this question and i don't seem to have the answer.
But we know it can be Nestted.
As long as your BIOS can detect the 2 USB disks as separate bootable devices, you can
I agree with @zXi_Gamer..
but as you have mentioned ESX "5.x", I would like to warn you against a potential failure that might occur in case of 5.0.
" Scripted ESXi installation or upgrade from an attached USB drive might fail if the file system type on any of the USB drive is not fat16 or fat32 " . This is known issue in 50U2 and is fixed in 5.1 and 5.5 and the fix may for 50u3 which I'm unsure about.
~dGeorgey