How can i list all display suite layout templates used
I think he's asking to get an overview of of which bundle / view mode uses which template file.

That's currently not easy to fine in the backend - however this is something we want to add add some place.

The fastest way to get an overview is to go to the database and look into the 'ds_layout_settings' table. The 'layout' column holds the machine name of the template used.