CUCM CTI, Controlling with 2 Users on the same extensions

We developed a system that using 2 application users (one for backup) to monitor CTI\JTPAI events from 2000 extensions.

The users logging in every morning automatically and both of them controlling all the extensions

Sometimes we experiencing a problem with one of the users that is not receiving CTI events at all for a specific extension. It's getting fixed only after relogin\app reset.

My question is if it's possible to connect with 2 users to the same extension in the CTI service? Is there any limit for that or documented information?

And if not, do you have any idea or lead to give us on the source of the problem? 

CUCM 8.6

I have moved your question under JTAPI community and request to refer the following url - JTAPI CTI Connection capacities for multiple providers for related information.