Exactly, and that's why they have to fix it. We talk about numbers here, which is a key indicator for many to see how popular a website is; We brought this to light so Google/Feedburner will finally address it
And what, exactly, do you want FeedBurner to do? They're just using the number NetVibes gives them and I doubt NetVibes is going to give them the ability to inspect user accounts to check for dupe subscriptions. So unless your solution for FeedBurner is "don't count NetVibes (or other aggregators that report inaccurately)", there's nothing for them to do.
Oh, be creative. Just off the top of my head: Feedburner could separate out aggregator reported counts, or show two numbers, one with aggregators and one without.