There's a major problem with MM handling podcast item. It duplicates a massive ammount of items. It all seems very random to me. It duplicates a couple items in each podcast subscription.
Here's a sample of it:

As you can see, there are 675 items of that same entry. And there are several of them that get duplicated. As a result, my database's filesize had ballooned very large.
I tried to delete them in MM but they reappears after a refresh. Then I tried an external database tool and it couldn't delete those entry due to a "IUNICODE" error:

Please help me to correct this problem.