The following KB details a solution for an issue where a user/admin may observe that the on-call schedule is not displaying properly when there is an overlapping schedule.
User has an on-call schedule shift for after hours support which starts on a Friday from 16:00 - 7:59:59 AM Saturday
User also has another schedule shift for after hours support on Saturday that goes from 08:00 - 7:59:59 AM Sunday
When this scheduled is viewed from a calendar the user/admin will see a discrepancy where the overlapping shift for Friday that shows up on Saturday displays the user is working from Friday 00:00 - 23:59 which is incorrect. Here is a screen shot of this behavior.
Release or Environment
The reason for the incorrect display is because the schedule for after hours support on Friday rounds the end time up when the time is a second before the next hour.
To prevent this from occurring the user/admin must set the schedule entry to end at a time that will not round to the next hour. This can be configured for 7:59:58 instead. Once this is done the calendar entry will now display correctly.