Sorry I didn’t actually look at the result set you wanted.
Here is the merged queries.
SELECT TOP 10
a.displaypath,
SUM(DateDiff(second,a.eventtime ,COALESCE(c.eventtime, CURRENT_TIMESTAMP))) duration,COUNT(*) total
FROM
alarm_events a
LEFT JOIN alarm_events c ON c.eventid = a.eventid AND c.eventtype = 1
WHERE
a.eventtime
BETWEEN '12/4/2015 00:00:00' AND '12/4/2015 23:59:59'
AND a.eventtype = 0
GROUP BY
a.displaypath
ORDER BY
duration DESC, a.displaypath ASC