We have previously published guidance for setting up multiple OWA and ECP virtual directories for Exchange Server 2007 and 2010, and now it is the turn of Exchange Server 2013.
The eagle eyed amongst you may spot some copy and paste from previous blogs on the subject, and well frankly, you’d be correct. The reasons for doing this haven’t changed, only the method by which you do it, so I’m re-using some of the text to avoid wasting electrons.
In short: Microsoft supports using multiple Outlook Web App (OWA) and Exchange Control Panel/Admin Center (ECP) front end virtual directories on a server with the Exchange 2013 Client Access Server role, when each is in its own website and is named ‘OWA’ and ‘ECP’. Each virtual directory must be listening on the standard TCP 443 port for the site.
Read more at source: http://blogs.technet.com/b/exchange/archive/2015/02/11/configuring-multiple-owa-ecp-virtual-directories-on-the-exchange-2013-client-access-server-role.aspx