Can you post a screen shot? I'm not seeing the behavior you describe when I try to replicate your setup.
One thing to note is that if you have a more restrictive view set up and you add some actions which would not normally be shown in that view, they will appear until you change the view. For example, if you are viewing a project and showing only Next Actions, you should have only one action shown. However, if you then add an action to that project in that window, the additional action will remain in view even though it may not be the true next action for that project. Doing the Edit->Clean Up command will update the view. It does sound a bit like you might have the project and the group switched around on the parallel/sequential setting, but a picture should probably clear things up.