Deployment key will allow you to create ssh-key to deploy your web application using GitHub or Bitbucket. Every system user can only have one deployment key and can be used again and again except in GitHub.
GitHub is preventing user from using the same deployment key. The workaround is to create another system user and generate another deployment key.
Please note that when you generate new key, old key will be invalid and your GIT Webhook won’t be working.
Deployment Key generation rate limit
You can generate deployment key 10 times in a minute. After a minute has pass, then you can only generate another one. This is to ensure that you are not spamming our server since SSH Key generation is a resources intensive task.