calendar has double entries

I have double entires in my calendar, I have schedules in my calendar and everyone of them are double, I sync with outlook and now my calendar in outlook on my PC has double entries. the calendars are only showing one of each of them any idead how to correct this issue other then removing them and re adding them?

The usual reason for double entries is because you are syncing to the calendar in two different ways. Are you using icloud and also syncing via itunes for example?