I don't know why
cfg_name_unique NOT LIKE '%categories%'
still returns those two values, but maybe exclude them explicit:
SELECT *
FROM developer_configurations_cms
WHERE developer_configurations_cms.cat_id = '1'
AND developer_configurations_cms.cfg_variables LIKE '%parent_id=2%'
AND developer_configurations_cms.cfg_name_unique NOT LIKE '%categories%'
AND developer_configurations_cms.cfg_name_unique NOT IN ('categories_posts', 'categories_news')