Category podcasting is a simple way to create 2 or more like podcast programs (feeds). Usually your 2 shows have the same main title, with sub-titles and they are similar content. If your doing two completely different programs, category podcasting is not a very good way to go because your search engine optimization and site branding cannot be separated.
Either way, Blubrry statistics has to be measured based on your blog site, it cannot be done by category. We've discussed this a number of times in this forum before. In a quick explanation, categories can overlap, when viewing a post via a page you don't know if the user came to that post via one category or another and it adds confusion to say the least. So only one stats account per WordPress blog currently.