Additional Client license in Service mode

Standard behaviour in Service mode is that it grant one additional Control Client license.   

Note: When you launch a display client on a computer that is running Plant SCADA as a Windows service, the client will request an additional control client license from the system. If this occurs on a machine with a valid license that has been obtained locally, you will be granted the additional license automatically.

As per this my observation when I have Full Server license and I switch to Service mode it adds 1 count to Control Client total quantity. However when I have Full Server license + Control Client license(s) it is not adding 1 count to the existing Control Client quantity. It shows Control Client quantity which is added in license manager. This creates problem when there is a exact quantity of Control Client license purchased and Control Client on the Server machine consumes one count so in some situations remote Control Clients fails with license error. I want to confirm if this is standard behaviour and if there is any workaround. 

1.
Full Server - 1
Control Client - 0 
In Kernel - Ctrl:  Max:1

2.
Full Server - 1
Control Client - 3
In Kernel - Ctrl:  Max:3 (expecting it to be 4)