Weird, really weird. I'm home now, and can copy my measurements exactly:
in 2d 500/1100 - 1,302V; in 3D 795/1100 - 1,331V-1,334V (jumping around as bench moves around)

For default BIOS, I had these:
in 2d 500/900 - 1,283V; in 3D 750/900 - 1,305V-1,308V
OCed in 3D 790/1100 - 1,307V-1,312V (so matches yours 0,001-0,003V difference from overclocking)

Now, it means I had up to 1,312V with stock bios when overclocked, and on almost same clocks (just 5MHz GPU, that shouldn't change a thing) I get up to 1,334V, so I got +0,022V from this BIOS. Also, my Catalyst showed unlocked Overdrive with this bios, and increased clocks as well.

Have you changed or modified this BIOS in any way before flashing? And are you sure it was actually FLASHED to your card? Perhaps it exited flash operation if you did not use FORCE option for flashing, because of different card IDs? You know you have to run ATiWinFlash in command prompt to FORCE flash any BIOS?
You would be certain if you would flash it by their own flash app by just running exe, not extracting and flashing manualy..

EDIT: If you DID flash correctly, than you can "download" your new bios by GPU-Z, and open it in RBE. If you don't see any changes in BIOS time/date/version and/or clocks, than you haven't flashed at all.. and that would be only explanation at this moment (to me at least )