I read your message, and I've been doing some searching. I think I might have found the keyboard. Go to this place: http://www.ergocanada.com/cgi-bin/store/commerce.cgi?product=Keyboard_Split&cart_id=6209495.17159
If for some reason that link doesn't work, go to ergocanada.com and search for it. It is a Cirque split keyboard. It might not have the same name as your keyboard, but it might be the same keyboard.
I hope this helps.
Up until a couple of months ago I have been using a keyboard called Silitek SPLIT keyboard sk-6000.
This keyboard was special because between the left and right side of the keyboard there were three extra keys, most importantly of which was a tab key.
The nature of my work requires excessive tabbing and since my sk-6000 cratered I have been lost without that key.
I have searched the world over, including trying to contact Silitek but unable to find anything even remotely similar.
Is there anyone out there that knows of such a keyboard layout and where I might go to find one?