Blocking registration of already registered VM from powershell.

Author: mkherani

src/ResourceManager/AzureBackup/Commands.AzureBackup/Cmdlets/Container/RegisterAzureRMBackupContainer.cs

@@ -159,7 +159,8 @@ private bool IsDiscoveryNeeded(string vmName, string rgName, out CSMContainerRes
             ContainerQueryParameters parameters = new ContainerQueryParameters()
             {
                 ContainerType = ManagedContainerType.IaasVM.ToString(),
-                FriendlyName = vmName,                
+                FriendlyName = vmName,      
+                Status = AzureBackupContainerRegistrationStatus.NotRegistered.ToString(),
             };
 
             //First check if container is discovered or not            

src/ResourceManager/AzureBackup/Commands.AzureBackup/Properties/Resources.Designer.cs

@@ -122,7 +122,8 @@
 1. VM does not exist
 2. VM is Azure IaaS v2 VM
 3. The VM name or the Service name needs to be case sensitive
- 
+4. VM is already Registered with same or other Vault. Please Unregister VM first and then try to register it again.
+
 Please contact Microsoft for further assistant.</value>
   </data>
   <data name="ResourceNotFoundMessage" xml:space="preserve">