On-Call Scheduling: Create new On-Call Schedule is creating duplicate schedule entry (cmn_schedule_span) records when inserting the schedule (cmn_schedule) record When creating a new on-call schedule, the first step is to define the shift in the wizard. After doing so and hitting 'Next Step', the cmn_schedule record is inserted and displayed in calendar view -- additionally, 4 child cmn_schedule_span records are created automatically. It is expected that only 1 child cmn_schedule_span record would be created automatically. 

The behavior seen is due to the updates made to the '24x7' schedule. Notice there are four schedule entries found in the 'Schedule entries' related list.

Out of box, this schedule only has one schedule entry, in this example there are four schedule entries. This is why the behavior is seen. Also, if you try creating a new schedule and select the other available schedules in the 'Schedule' drop down option, you can see this behavior is not being seen. This is specific to the 24x7 due to the additional schedule entries which are customer created. The solution is to remove the three schedule entries created by the internal user.