I'll be submitting this plugin to the Plugins area for review later today or in the morning (needed the support thread for the readme).

It's an admin tool that allows you to copy all template-override files (and Layout Boxes Controller configuration) for an existing template on your store to another template name. I think it will be especially useful to create "clones" of the Responsive Classic template that's built into Zen Cart 1.5.5.

The plugin is multi-language-aware, so if your store is multi-lingual and the "source" template includes multi-lingual files, they'll all be copied to the newly-minted "target" template.

I will post back here once I've got a download link from the Plugins.