This seems to be a question about ICS / IICS. If my understanding is correct, please move this question to the Cloud Data Integration forum, there you probably will get the answer you need.
So a couple things here.
1) You are trying to configure the token for an already register secure agent since you see it in the admin page. At this point you should be using ./infaagent to start or stop the agent. Why are you trying to register the agent?
2) If you are trying to register a second agent installed on the same machine as another. It does not work this way. Only one agent on a machine can be registered at a given time.