I'm having this proble for the first time. I got a used Mac pro, clean installed Mountain Lion on a brand new hard drive 2 days ago. Today an update for CodeBox showed up, an app I don't have and have never downloaded. Right clicking does nothing.
In my obsessive compulsiveness I figured I'd just download it and then delete it just to get it out of the list. When I click update it brings up the authorization window, so this must be a paid app. The truly bizarre part is that the email that is in the pop up window ISN'T MINE. Maybe the App Store is freaking out, I don't know. Either that, or like someone who loses a limb and still feels the phantom body part, my used Mac Pro is remembering updates for programs on a hard drive it no longer has.