Si conoce el valor de n, podría hacer algo como esto (para n=3):
Select *
FROM players
WHERE Left(name, 3) in (
SELECT Left(name, 3)
FROM players
GROUP BY Left(name, 3)
HAVING (Count(*) > 1)
);
Si conoce el valor de n, podría hacer algo como esto (para n=3):
Select *
FROM players
WHERE Left(name, 3) in (
SELECT Left(name, 3)
FROM players
GROUP BY Left(name, 3)
HAVING (Count(*) > 1)
);