Azure Active Directory Sync Behaviour - users not expected!

This has recently occurred and I would like to understand the behaviour. It is in relation to setting up an Active Directory in the cloud against aDomain NOT yet verified.

Scenario:

OnPremise Domain Controller (ADOMAIN.COM) www.ADOMAIN.com.

Existing Microsoft Azure Subscription (admin@abc.onmicrosoft.com)

Azure Active Directory already exists for ABC.com

Setup new Azure Directory for ADOMAIN.com on same subscription

Process I followed

1. Created Active Directory in Azure
   1. Directory Integration – Active
   2. Domain ADOMAIN.com added
   3. Verification records sent to domain hosting provider
   4. Left in Unverified state.

2. Installed & Setup Azure Active Directory Synchronisation tool.
   1. Linked synchronisation to admin@abc.onmicrosft.com

I am at this stage now, where DirSync is happy and setup, with the AD in Azure still unverified. The behaviour I have identified is that all the user accounts in the domainADOMAIN.com have been automatically created and synced to the default ADABC.com in Azure as <user>@abc.onmicrosoft.com.!

• Is this expected behaviour?
• Would I have done this the wrong way round?
• What will happen when I can verify the ADOMAIN.com in Azure?

I would appreciate it if you could assist me in this matter as it is our first venture.