The receptionist opens the Calendar to add the period of time that the doctor will be there, in this case 60 minutes. Remember that calendar asks you to specify the time in minutes.
When the event is recorded, the Calendar shows a longer period of time than the chosen one.
This happened on my test server, and to rule it out I tried it on the official DEMO, and the same error occurs.
Here is an Youtube that shows you that error in the official DEMO.
Any comment ?