Scenario: 

•  We have Multiple Versions of Microsoft Office installed on the Master Image or vDisk and looking forward to activate both versions using KMS

This scenario is not supported. Please refer Microsoft's KB https://support.microsoft.com/en-us/kb/2784668 according to which : "We do not support the use of multiple versions of Office on versions of Windows that have Terminal Services enabled. If you want to run multiple versions of Office on Windows, you should disable Terminal Services."

We can have multiple Versions of MS Office installed on a Windows Desktop OS and activate them using KMS, however if we need to have multiple versions of Office installed on a Windows Server OS, then we need to disable Terminal Services, else please refer the following workaround.

Workaround:

• Use separate Master Images or vDisks with single version of MS Office installed
• Use these Master Images to create the Catalogs and then Create the Delivery Groups accordingly and assign users to have access to multiple Office Versions 

KMS Activation Reference : 

• Configuring KMS Licensing for Windows and Office 2010 and 2013 : http://support.citrix.com/article/CTX128276
• ​XenDesktop Support for Microsoft KMS and MAK Activation with Machine Creation Services : http://support.citrix.com/article/CTX128580

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Microsoft KB: https://support.microsoft.com/en-us/kb/2784668