Not without mulitple swfs or a swf with a larger than the single screens resolution. I have been able to create a swf that was 1900 wide that displayed on two 800 wide resolution monitors. It was nothing more than two text boxes, but it worked. Have not revisited it since. A swf is a single file, and will display as such, can;t be broken apart to my knowledge. AIR may have some capabilities in that vein, but not sure.
Nope there is no multiscreen support in a normal flash file as it's not capable of recognizing the amount of screens available, in AIR you have access to all the hardware installed therefore it's possible again to use a multiscreen setup. There are also other software pieces that might help you developing multiscreen SWF's
ZINC: www.multidmedia.com ( although I strongly reccomend you not using ZINC )