sqlfiddle:http://sqlfiddle.com/#!2/9a8b3/1

Tomando a estrutura e dados e consulta do violino, importando para o meu MariaDB 5.5.31, obtive resultados diferentes:

sqlfiddle

PID  NAME       LEAGUEPOINTS        TOTALLEAGUEPOINTS
2   Peter   16,13,9,4,2            44
1   Daniel  3425,543,234,43,29,22,21,21,19,17,13,12,12,12,11,9,9,9,8,7      4476

mariadb

pid  name    leaguepoints       totalleaguepoints   
2   Peter   16,13,9,4,2             44
1   Daniel  3425,543,234,43,29,22,21,21,19,17,13,12,12,12,11,9,9,9,8,7,7,6,5,5,4,4,4,3,3,2,1    4520

Inquerir:

SELECT                
    p.pid,
    p.name,   
    GROUP_CONCAT( gC.leaguepoints ORDER BY leaguepoints DESC ) AS leaguepoints, 
    SUM(gC.leaguepoints) AS totalleaguepoints
FROM test_golf_player p
LEFT JOIN 
(
    SELECT pid, leaguepoints, @Sequence:=IF(@PrevPid = pid, @Sequence + 1, 0) AS aSequence, @PrevPid := pid
    FROM
    (
        SELECT pid, leaguepoints
        FROM test_golf_card 
        ORDER BY pid, leaguepoints DESC
    ) Sub1
    CROSS JOIN (SELECT @PrevPid := 0, @Sequence := 0) Sub2
) gC
ON p.pid = gC.pid AND aSequence < 20
GROUP BY p.pid
ORDER BY p.name DESC 

Alguma ideia do porquê?