Should a dmcc .net registration request receive a negative acknowledgment from AES if there is a different agent logged into the extension requested in the registration?

agent:A is logged into station:A
dmcc API sends request to register Station:A with Agent:B and gets a success
CM has not registered Station:A with Agent:B

Correct me if I am wrong.

Agent A (2000) is logged into station extension A (1000)

Your application makes a CTI (TSAPI) request to log agent B (2123) into extension 1000.

You say you get a positive acknowledgement (to what?). Have you enabled TSAPI tracing to see what really happens with your agent login request? I would - look for a FAQ talking about 'tracemask' on the DevConnect portal.

What do you mean by this statement "CM has not registered Station:A with Agent:B"... that the CTI request to log agent B into extension 1000 does not change CM's state --- is Agent A (2000) still logged in on extension 1000 (at the sat look at 'list agent ')?

I expect the request to fail as there is already an agent logged into extension 1000. What you may be seeing is a "Thank for for your well formed message; I am going to go process it now, so please wait on a final response before assuming anything good happened here."