Multiple Calender syncs

[hunter.england]

This is driving me crazy now!! Right, i use the stock Splanner on the Galaxy S5 which is synced with my work outlook calender on my work PC by USB cable, all worked fine. Now i have added my work outlook emails using the 365 account on the stock andriod email. But now when i sync the i get some of the calender entries 2, 3 ,4, 5 times. Seems to add another each time i sync. I tried the various tick boxes, forced Outlook to phone (which lost 90% of the entries). Help...