How to identify and copy a pane?
It turns out my pane was a fieldable panel pane. As far as I can tell, these panes serve as templates, and when placed in panels, they are copied into one-off panes. 

So my solution was to add another copy of the fieldable panel pane, this time making sure to check the 'reusable' box. Then, I replaced all the one-off panes throughout the site with the reuseable pane.