Did you try force closing and refreshing the Calendar app?
Force closing:
Double tap the Home button to show the App Switcher, then slide the thumbnail below the app icon towards the top of the screen.
Refresh calendars:
In the Calendar app, tap Calendars at the bottom. You'll find all calendars set up on your iPhone. Then tap somewhere on the screen and drag towards the bottom. A spinning wheel will show that the app is refreshing events. When it has finished, tap Done at the top right, and take a look at your events.
If that doesn't help:
Which account shows triple events? Do you share these calendar events?