This question is always asked, problem being with everything licensing it either is automatically erased after getting the answer or citrix has gone and changed the rulebook.
The Answer is No, a single XenDesktop or XenApp site cannot support multiple editions from a single deployment. A single XenApp or XenDesktop site can only support one edition and one licensing model- user/device or concurrent.
UPDATE : 09/05/2017 – With the release of XenDesktop/XenApp 7.14 it will allow XenApp and XenDesktop Licenses to be mixed , including User/Device and Concurrent.
For Example: XenApp Platinum Concurrent & XenDesktop Platinum User
There is a limitation that it should be the same edition (so both platinum edition, not a mixture of Platinum & Enterprise)
See further confirmation on eDoc’s http://docs.citrix.com/en-us/xenapp-and-xendesktop/7-14/whats-new.html & http://docs.citrix.com/en-us/xenapp-and-xendesktop/7-14/manage-deployment/licensing/multi-type-licensing.html
Also see https://support.citrix.com/article/CTX223926 – How to Configure Multiple License Types within a Single XenApp and XenDesktop Site