Sure it's possible (well not sure with the two cards that you are running but in general it's possible). And it doesn't matter what distro you are using. It's a function of Xwindows. Are both cards PCI (what does "/sbin/lspci -v" spit out)? I personally have only done a dual head in Linux using a single video card capable of driving two and even four monitors.
Search google "dual head xfree 4.2". Look for "dual head" on
http://www.xfree.org/ as I am pretty sure that's where I got the necessary information. You'll definitely be tweaking your /etc/X11/XF86Config file.
You'll need a "Monitor" section for each monitor, and a "Device" section for each card, and then the "ServerLayout" is the important part. It's where you tell X how to talk to each card and how you want your monitors laid out.
Do a "man XF86Config" (case sensitive) and you will find a "ServerLayout" dual head example. It also tells you how to use the "BusID" tag for your "Device" section to specify how to address each card. It sounds a lot harder than it really is. You might be able to find some example XF86Config files out there with a good search.