Aggregating Network Blog Feed on Multisite

I'm currently using the main blog of this multisite to aggregate RSS feed from multiple outside (non network) sites, using autoblog. I'd like to start including network sites as well. I have the post indexer plugin installed, as well as the global feed plugin — and had considered adding the global feed rss to autoblog. If I add the global feed rss, will it duplicate the rss feed that is already being aggregated on the main blog? I suspect it will. So I'm looking for a way to get the global feed rss to exclude the main blog. Is this possible? Or is there a better way to accomplish this aggregation?