SELECT DocumentNo, DateModified
FROM (SELECT left(qryLetters.DocumentNo,11) AS DOC11, qryLetters.DateModified, qryLetters.DocumentNo
FROM qryLetters
WHERE qryLetters.DocumentNo IN
(SELECT TOP 10 DocumentNo
FROM qryLetters AS Dupe
WHERE left(Dupe.DocumentNo,11) = left(qryLetters.DocumentNo,11)
ORDER BY Dupe.DateModified DESC, Dupe.DocumentNo DESC)
ORDER BY left(qryLetters.DocumentNo,11), qryLetters.DateModified, qryLetters.DocumentNo) AS TOP10
ORDER BY DOC11, getnumber([DocumentNo]);