I don't think there is right now, and that's a real flaw that I'm hoping Omni will fix. Please send feedback to them to help encourage a more useful functioning of the "due or flagged" filter.
There are other threads that touch on the topic, such as these:
http://forums.omnigroup.com/showthread.php?t=13281
http://forums.omnigroup.com/showthread.php?t=11599
http://forums.omnigroup.com/showthread.php?t=11887