I see this from time to time. There will be an old version of an application listed (red), and a new version too (green).
In this case, it is Audacity.
Here's a screenshot: https://www.screencast.com/t/w2KEfCe6
Why doesn't the old version get replaced when PMPC installs the new version?
This is how the old Audacity installers were designed, they weren't replace the new update with old one! They were just install alongside it! Resulting 2 or more updates to be installed in the same time! But they fixed that starting from v3.1 as I remember..
So you just need to manually remove the old one v3.0.2 from "Add/Remove Programs" and it will not happen again :)