Is downgrading the BIOS safe?

I just got my first ThinkPad (W520) and I want to join in on this custom splash screen craze. Unfortunately, the person who sold it to me updated the BIOS. So when I go to run the BIOS updater (with custom logo.jpg) it tells me that the BIOS is the same as the updater.

I haven't found a definite answer to this. Can I safely downgrade my BIOS?