Stop Multiple CI Runners from using the same token

ZD ticket: https://gitlab.zendesk.com/agent/tickets/80092

A user's specific runner AMI was copied (intentionally) but the runners config contained the runner token. So now two runners are reporting as runner $ID and picking up jobs. I tested this and confirmed on a repo I made:

From the ticket:

After a bit of investigation, It looks like one of our developers created an AMI of our GitLab Runner & stood up his own based on that AMI to do CI testing/exploration. It then looks like he registered another runner on that instance without realizing the "original" runner was also running. So it would randomly pick up these jobs and most of the logs from the Job run would make it appear that it's running in one place when there are really 2 instances of that runner reporting into GitLab and picking up jobs.

The user asks:

Should GitLab not have some kind of check to disallow a runner with the same CI Token/identifier from running/connecting? Or at least not allow duplicates?