SELECT P1.page_title AS first_title, P2.page_title AS second_title

FROM page AS P1, page AS P2

WHERE P1.page_namespace = 0

AND P1.page_title LIKE '%\_(%)'

AND P1.page_title NOT LIKE '%)%(%' AND P1.page_title NOT LIKE '%(%(%'

AND P2.page_namespace = 0 AND P2.page_title LIKE CONCAT(SUBSTRING_INDEX(P1.page_title, '_(', 1), '\_(%)')

AND P1.page_title < P2.page_title AND P1.page_is_redirect = 0 AND P2.page_is_redirect = 0

AND SUBSTRING_INDEX(P1.page_title, '_(', 1) = SUBSTRING_INDEX(P2.page_title, '_(', 1)

AND NOT EXISTS (

  SELECT 1 FROM page AS P3 WHERE P3.page_namespace = 0 AND P3.page_title = SUBSTRING_INDEX(P1.page_title, '_(', 1)

)

ORDER BY P1.page_title;