title: Office365 returns same recordd ID for Two different Contacts?
body: <p>Recently we have developed integration with Office365 to sync Contacts and Calendar events from Office365 and every thing seems to be working as expected. But today I faced one different issue where I followed this test case.</p>
  
  <p>I created couple of contacts in Office365 and synced back to our application. Later imported around 500 contacts in Office365 and synced again. After the sync I noticed that 4 contacts were updated even though there was no update (which have been created). Because of this update my existing 4 contacts were overwritten.</p>
  
  <p>I went through the logs and noticed that office365 record IDs of 4 records that were synced earlier had the same record IDs for the 4 contacts that were created after the import in office365. </p>
  
  <p>My question is even though <strong>ID</strong> is unique identifier for office365 record (according to their <a href="https://msdn.microsoft.com/en-us/office/office365/api/complex-types-for-mail-contacts-calendar#RESTAPIResourcesContact" rel="nofollow">document</a>) why two contacts has same record ID?</p>
  
  <p>Is there any other unique identifier for Office365 contacts record?</p>