In Part one I have already described how to remove phantom apps here on more supplement. These phantom apps could also remain in the AppFabric Monitoring db:
Just delete no longer needed entries in this table.
Just delete no longer needed entries in this table.
Duplicate collection entry
When you receive this kind of issue, like "[...] Cannot add duplicate collection entry [...]" you have defined the a configuration section twice in two different Web.config files in different places in your file system.Clear
One easy solution is to use a clear statement.
Searching for the inherited element
There is a post in Microsoft's documentation which is explaining how to do it.
Visual Studio in debug mode
When you are working with Visual Studio in debug mode, which means you are just pressing F5 to run it on your local IIS instead of publishing it to a web server, you should keep in mind that e.g. your obj folder might contain more copies of your Web.config file. This could lead into this duplicate collection issue as well.