The lack of styling for the XML document isn't usually an issue; is there any specific reason why you want styling for that document? It has nothing to do with how the RSS feed is eventually displayed.
From what I can see, the main issue looks like it's the duplication of feed items in your sidebar. Could you post the URLs of the RSS feeds that you're importing to WP RSS Aggregator so we can test them? Could you also permanently delete the feed items that have been fetched and then refetch them? Generally when something like this happens it means the initial import of the feed items went wrong at some point and we weren't able to set everything up so that we could check for duplicates. Since we only have two stories for each feed item, it looks like the second time the feed was fetched everything processed correctly.
That's what you mean by "broke sidebar" I assume, right? The post duplication? Since I can't see anything else wrong with it.