SteveB: A really good habit to get into, if you tend to use the same partials on all sites, is first create a template, with one page and all the partials you want on it. Save it as a template, then use it as the starting point for all new projects. It’s how i work with Foundation projects.
Thanks SteveB for the great suggestion! Just what I was looking for.
Although that’s a practical and easy workaround, I’d still like Stacks to add the feature of “Duplicate” Partials within a project in the next upgrade. It seems like reusing and modifying copies of Partials would be a natural reason for using them.