Although a specific folder is selected, the Vivado 2014.1 installer will overwrite an earlier installation of DocNav and it may not use the same install folder with other components.
When a specific folder is selected, it should use the same folder for everything.
DocNav installing to a different folder is inconsistent.
This is the expected behavior.
DocNav is a standalone product tool and is independent of a specific Vivado or ISE software version.
In the destination panel, there will be an icon below the standalone product path if it does not match the specified destination directory.
With the icon, the following text will be displayed: "This installation will update a previously installed version of this product."