Perhaps it's a licensing issue? It could be that the SDK does not correctly log out from the sessions you connect to. The 3.0 version of the SDK introduced a log out mechanism when disposing locations (Qlik.Engine.Location implements IDisposable). You might want to try out that version.
Thank you for your reply.
I know i have alternate option to upgrade. Also in 3.0 we have another option to authenticate that is AsExistingSessionViaProxy() which working very fine in my another application.
Do we have any option to pass existing sessionid with request of AsStaticHeaderUserViaProxy() in 2.2.3 so that server will not create new session for the same user.