ciao, prova a modificare questa parte

SELECT A.*, B.*
FROM members AS A
INNER JOIN profiles AS B
ON A.mem_id = B.mem_id $nazionevar $settorevar
WHERE ".$query_str;

così...

SELECT A.*, B.*
FROM members AS A
INNER JOIN profiles AS B
ON A.mem_id = B.mem_id $nazionevar $settorevar
WHERE ".$query_str GROUP BY A.mem_id;