Under typical Gigabyte naming conventinos, F6a was a beta BIOS. They replaced it with the non-beta F6. If you scroll to the right on the System Information screen, what year is attached to that date? 7/29/200_?
I took another look at your image and see you have the GA-EP35-DS3L. There's a forum where one of the members keeps up to date versions of most Gigabyte BIOSes. The also have the 6/19/2009 - F6 version as the latest and greatest. http://forums.tweaktown.com/f69/gigabyte-latest-bios-28...
If the date that is cut-off in your image says 7/29/2008, then your F6a is an older BIOS that was released shortly after the F5 (7/17/2008). Probably the first in a series of Betas.
They spent about a year working on BIOSes before finally releasing the non-beta version and naming it F6. They did the same thing recently with the GA-P55M-UD2 and the F4 series of BIOS releasing, e.g., F4g, F4k, F4n, and then finally a non-beta version named simply F4.