XML export Themeing not using overridden templates for the alternative styles

When setting an alternative template for the header, body or footer for an xml export view, the user interface appears to find the template file and highlight it in the user interface but the export does not use this template when creating the xml file.

If I edit the template files in the module directly (e.g. sites/all/modules/views_data_export/theme/views-data-export-xml-header.tpl.php) then the changes are reflected in the output file

Steps to reproduce:

On a fresh install of drupal 6.20

$ drush dl devel,views,views_data_export,admin_menu
$ drush en devel_generate,views,views_data_export,views_ui,admin_menu
$ drush genc 20 2
import attached view (view.txt) in the interface, give it the name example and press save once loaded
$ drush vde example default test.xml --format=xml
inspect test.xml to see its as expected
copy attached views-data-export-xml-header--example--views-data-export-1.tpl.php to themes/garland
In the interface, check that the theme informaion is picking up this new theme file at admin/build/views/edit/example (rescan the template files and save)
$ drush vde example default test2.xml --format=xml
You should see that test2.xml is the same as test.xml despite using a different header xml file. There should be a tag at the top of the xml

I have tried supplying custom templates of all four template types (views-data-export.tpl.php, views-data-export-xml-header.tpl.php, views-data-export-xml-body.tpl.php, views-data-export-xml-footer.tpl.php) but they are all ignored in favour of the files in the modules own theme directory