Portals with mainspace pages which redirect to each other

This query lists pairs of portals (P1, P2) which share their names with a pair of mainspace pages where one (Pm) redirects to the other.  Such portals may be duplicates.

SQL

SET STATEMENT max_statement_time = 20 FOR
SELECT P1.page_title, P2.page_title
FROM categorylinks CL
JOIN page P1
ON P1.page_namespace = 100 AND P1.page_id = CL.cl_from AND P1.page_is_redirect = 0 AND P1.page_title NOT LIKE "%/%"
JOIN page Pm
ON Pm.page_namespace = 0 AND Pm.page_title = P1.page_title and Pm.page_is_redirect = 1
JOIN redirect R
ON R.rd_from = Pm.page_id AND R.rd_namespace = 0 AND R.rd_title NOT LIKE "%/%"
JOIN page P2
ON P2.page_namespace = 100 AND P2.page_title = R.rd_title AND P2.page_is_redirect=0
WHERE CL.cl_to = "All_portals"
/*ORDER BY P1.page_title, P2.page_title*/

SQL

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