It is very well possible you would like to either move a set of virtual machines to another Azure data center or duplicate a set of virtual machines from a data center and deploy those in a different data center. Think about these scenarios:
Deploy to multiple data centers. You have built a set of virtual machines that serve an application in a single Azure data center. For high availability or disaster recovery reasons, you may want to duplicate this deployment to a different Azure data center.
Avoid downtime because of maintenance. You have an application running on a single VM in a single Azure data center. You want to avoid the downtime when Microsoft performs maintenance. So the application needs to be deployed in a different Azure data center as well.
Moving between subscriptions. Suppose you created virtual machines under a single Azure subscription and want to move those virtual machines to a different Azure subscription...