What exactly are these entries for? There's an entry in the postmeta for all of our posts and has caused duplicate posts to appear on our site.
I think I only noticed this problem once the day before we upgraded to 2.5.1. Then, once we upgraded, every post submitted through the dashboard showed up as a duplicate post. We eventually altered the actual query to stop this from happening. But, still there are many entries in postmeta. Should this be happening?