Hi Oliver,
The ATY Rage 128 Pro can not run two monitors.
If your graphics requirements are modest, and you just want to run two VGA monitors independantly, then I would recommend the ATI Radeon 8500 Mac Edition. It has DVI, VGA and S-Video output, so you would run the second VGA monitor off the DVI port using an adaptor.
Here is a link that provides information on this card:
http://www.ati.com/products/radeon8500/radeon8500me/index.html
This card is discontinued, but can still be sourced (maybe "Google" for it). eBay may also be a good place to look, but be sure that the seller has a good reputation and a sound returns policy (if the card were to be DOA). Be wary of "flashed" PC cards (PC cards flashed with a Mac ROM), sometimes they work fine, sometimes they don't.
Cheers!
Karl