Prueba esto en su lugar:
with times as (
SELECT t1.EmplID
, t3.EmplName
, min(t1.RecTime) AS InTime
, max(t2.RecTime) AS [TimeOut]
, cast(min(t1.RecTime) as datetime) AS InTimeSub
, cast(max(t2.RecTime) as datetime) AS TimeOutSub
, t1.RecDate AS [DateVisited]
FROM AtdRecord t1
INNER JOIN
AtdRecord t2
ON t1.EmplID = t2.EmplID
AND t1.RecDate = t2.RecDate
AND t1.RecTime < t2.RecTime
inner join
HrEmployee t3
ON t3.EmplID = t1.EmplID
group by
t1.EmplID
, t3.EmplName
, t1.RecDate
)
SELECT EmplID
,EmplName
,InTime
,[TimeOut]
,[DateVisited]
,convert(char(5),cast([TimeOutSub] - InTimeSub as time), 108) totaltime
,convert(char(5), case when TimeOutSub - InTimeSub >= '08:01' then
cast(TimeOutSub - dateadd(hour, 8, InTimeSub) as time) else '00:00' end, 108) as overtime
FROM times
