Delete core_config_data values where the fallback value in scope 0 is the same

clean-core-config-data-duplicate-values.sql

DELETE FROM core_config_data WHERE config_id IN (SELECT config_id
  FROM (SELECT DUPS.*
        FROM core_config_data ORIG
                 LEFT JOIN core_config_data DUPS
                           ON ORIG.path = DUPS.path AND (ORIG.value = DUPS.value OR (ORIG.value IS NULL AND DUPS.value IS NULL))
                               AND DUPS.scope != "default" AND DUPS.scope_id != 0
        WHERE ORIG.scope = "default"
          AND ORIG.scope_id = 0
          AND DUPS.path IS NOT NULL) as tmp)