I have four different Outlook Calendars covering about five years each with overlapping content. They span Hotmail, Gmail and iCloud. I want to merge these calendars into one master calendar that will contain all events without duplication. Could someone please tell me how to do this?

I navigated to the Export Outlook Data File (I have done this often) but the three choices regarding duplicates are confusing me because every event in a calendar is unique -- it is impossible within a single calendar to have the same event to occur at more then one time. If an event is a recurrent event, isn't each recurrence unique because it occurs at a unique time? So what do these choices mean:
Replace duplicates with items exported
Allow duplicate items to be created
Do not export duplicate items

I continued, choosing the first option to export the calendar from my hotmail account in pst format.

If I export each calendar, how do I create a new master calendar from the exported calendar files without duplicates?

I am using Microsoft Outlook Home and Business 2013 version 15.4745.1002; Windows 8.1, Version 6.3.9600 Build 9600, 64.

Thanks, billy589