[Satellite 6] can't delete 'duplicated' content hosts [404 Resource Not Found]

Issue

The 'subscription-manager register' command was accidentally run twice on two terminals. As a result, the corresponding host is now registered twice in the Satellite.
Now the tasks to destroy content hosts fail with this error:

Katello::Resources::Candlepin::Consumer: 404 Resource Not Found {"displayMessage":"Consumer with id 50070ab9-74be-4fb6-9135-eb4346235628 could not be found.","requestUuid":"7c6be7a0-4ba1-4ca8-8028-4f2b29e1d15f"} (DELETE /candlepin/consumers/50070ab9-74be-4fb6-9135-eb4346235628)