I believe this has to do with the new repository plugin.
I added a plugin, but the original information was incorrect and I deleted the page and started over with the correct data. The deleted page had an incorrect name for the plugin, which was dwcommit. The new page has the correct name, which is dwcommits (note the plural). Now there are two entries on the plugins page, one for dwcommit and one for dwcommits. Both entries link to plugin:dwcommits.
So, there may be two issues here. First, is a plugin deleted from the database, when its page is deleted? Second, is there a way to correct the plugin name, in the event that it is originally stored with a typo?