You synced these podcasts with MM or iTunes? MM does not use the PODCASTURL tag, so I don't think that would be the issue. (assuming you synced with MM)

I have a couple podcasts that are showing up twice on my iPod Classic when I sync. I found this: http://discussions.apple.com/thread.jspa?messageID=10851888

But there doesn't seem to be a url item in the tag. Anyone have any ideas on how to fix this with mediamonkey? I checked the tags for a while (one's that weren't showing up vs ones that where) and couldn't seem to find anything special in the tag.