I have the Downloads notification set to notify me when things are updated. Maybe something gets updated everyday. Do you think?
This sounds like a problem I have been having as well.
About a week ago I went to update some apps and the market place started shooting me multiple copies of each one (it was around 4 simultaneous installs of the same app). Ever since then I show +4 updates. I haven't bothered with hunting down the specific ones though. Been to busy with work /lol