Global settings seem to trump node settings

When using metatag I have found that the global config seems to override the node config. e.g. If I remove a metatag from an existing node, the metatag is still output as per the global configuration.

Please can you clarify is this is the expected behaviour here as I would expect node to always trump the global config, although I would also expect the global config to be applied when the node is first created.