I have found this guide to be very useful in unlocking the HD6950 cards. They do credit TechPowerUp for it.
http://www.legitreviews.com/article/1608/5/
I have two Cards in CrossFireX and my validation is here 2rra4. The Part number to my cards are "Sapphire HD6950 P/N 102-C21601-00-AT" If...
Well, I dunno if you un-installed the frivers before you flashed each one? If not, boot into safe mode un-install the drivers and then un-install the App profiles.. Reboot into safe mode and then un-install the video card(s) from device manager. Use a reg cleaner like CCleaner on next boot and...