This is the feature I am looking for as well. I imported a bunch of episodes (270+ without a hitch!) from PodPress, importing the MP3s to one feed and the WMV files to a custom feed. So, the enclosures are proper and iTunes (nor any other feed reader) will not get confused.
Yet, the WordPress post still has both media files tied to it. It would be nice to have all the files display on the page so people can still view the old videos. Please note I am only talking about the web page here, NOT any RSS feed.