Lync 2013 Presence State:

Lync 2013 Presence State:

When user logs on mulitiple device like desktop, laptop and mobile device using IM client then you will able to get the pop-up message at the latest acive available device and the endpoint you accept the conversation. This is as per design.

In OCS we have Single Point of Presence (SPOP), only a single device could be logged in at one time where as Lync Multiple Points of Presence (MPOP)

Ref:  http://blogs.technet.com/b/uc/archive/2007/03/01/multiple-points-of-presence-mpop.aspx