It uses alternate frame rendering, very similar to their current stuff. One problem with Rage Fury MAXX is that it has crap drivers. This era was definitely before ATI got their driver development up to a reasonable quality level.
The other serious problem with the card is that NT5 (2k,XP) doesn't support 2 AGP devices so you can only use half of the card unless you're on Win9x/Me. It becomes the same as a regular Rage Fury.
Here's an old ATI support email:
Dear Customer, […]
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Dear Customer,
You have previously contacted our Microsoft Windows 2000 feedback email address to comment or inquire about RAGE FURY MAXX drivers and support for the Microsoft Windows 2000 operating system.
I regret to inform you that our plan to provide a RAGE FURY MAXX driver for the Windows 2000 operating system cannot be completed. Due to issues with enumerating the chip ID's, of the dual RAGE 128 PRO graphics chips, we are unable to complete the driver for our RAGE FURY MAXX card.
ATI sincerely apologizes for promising a driver to you and then being unable to complete it. This was an unforeseen technical issue during the development of the Windows 2000 RAGE FURY MAXX drivers.
For those customers who wish to contact me directly to comment on this situation, please email me at cservice@ati.com. I welcome your comments and feedback
I'd love to see a nice high-res photo or scan of your card!