A BIOS chip is just a programmable IC. It could have any function it was programmed for, not only a BIOS program.

I don't know of any machine that has two different BIOS chips. Some newer board have a backup one to rewrite the BIOS program to the main one should it get corrupted or erased, but can still be on the same IC.

It wouldn't make much sense either unless maybe you had two different hardware setups you wanted to switch between at boot without ahving to reconfigure the BIOS.