Getting wrong scheduled datetime in Job data

We are using API url to fetch Jobs data.

https://developer.servicem8.com/reference/get-job-all

But we are getting different scheduled datetime('job_is_scheduled_until_stamp') in JSON response

E.g. actual scheduled time is 1:00 PM with duration of 1 hour(While booking). We're getting 2:00 PM and if duration is 30 mins, we're getting 1:30 PM in API response. We want actual time without added duration. OR can we get separate duration time field in job data?