title: How to prevent duplicate entries?
body: <p>I am beginner android developer.I am writing app witch write calls(incomming,outgoing,missed) to Android Calendar with some useful informations about call.Now i am trying to prevent from duplicate entries.For example if i run this app 2x and the calendar will be filled with duplicate entries.Has anybody got some great idea how to do it?I thought about this, i save date of last call witch is written to the calendar and then it will continue from this date.
  Sorry for my English.</p>