In this scenario, we use the Lync Server 2013 and Lync client 2013 with SkypeUI enabled.
All was working fine, but, after install security update for Skype for Business 2015, the Skype for Business title is changed to Lync.
If you disable the SkypeUI, the Lync client is displayed.
If you enable, the Skype UI is displayed but, with Lync in title…..
Security Update for Skype for Business 2015 (KB3101496) 64-Bit Edition