Radeon HD 2600 PC Compatibles with Mac?

Arasp, one of our French forum members, purchases a Mac Pro rev2 and its Radeon HD 2600 XT. He wanted to get a second one, so he gave it a try and purchased a Radeon HD 2600 for PC.
Once installed in the second PCI Express 16x slot, when displaying information about the system it shows:

Pre-installed card (Mac Pro 2008) :
ATI Radeon HD 2600 :
GPU type: ATI Radeon HD 2600
Type: Monitor
Bus: PCIe
Location: Slot-1
PCIe: x16
VRAM (total): 256 Mo
Manufacturer: ATI (0x1002)
Peripheral ID: 0x9588
Revision ID: 0x0000
ROM revision: 113-B1480A-236
EFI version: 01.00.236

PC Card Sapphire :
ATI Radeon HD 2600 :
GPU type: ATI Radeon HD 2600
Type: Monitor
Bus: PCIe
Location: Slot-2
PCIe: x16
VRAM (total): 256 Mo
Manufacturer: ATI (0x1002)
Peripheral ID: 0x9588
Revision ID: 0x0000
ROM revision: 113-B1480A-236
EFI version: 01.00.236

The PC graphic card, a model from Sapphire, is recognized as the Radeon HD 2600 Mac Edition pre-installed in the Mac! We still have a doubt, as the system might have loaded the graphic card ROM only once for both cards. Nevertheless this is an interesting news, especially for those aiming to install 2 graphic card for setting up a multiple display system.