select accountid,count(*) as count from vtiger_assetaccount group by accountid having count>1;
更新
如果要找出是哪些记录重复
SELECT result.accountid FROM ( SELECT accountid, count(*) AS count FROM vtiger_assetaccount GROUP BY accountid HAVING count > 1 ) AS result LEFT JOIN vtiger_assetaccount ON vtiger_assetaccount.accountid = result.accountid