I will be having an intern writing copy, but then want a supervisor to approve and publish it using the same computer (and copy of Contribute). But when I try to import the second connection key, it threatens to override the first one. Is there a work-around so the intern/writer can leave a draft for the supervisor/publisher, who later signs into the website, approves, and publishes the pages?
Connecting to the same site with two different role in the same machine is not possible. It will ask for overridding the existing connection.
You can ask the writer to create the draft and send it for review to the Publisher by clicking the Send for Review button. So when the Publisher connects using his connection key, the draft sent by the Writer will appear in the pages panel. So he can review it and Publish the page.