ERR_NGROK_SHIP_APP_ENVIRONMENT_URL_DUPLICATED: Environment URL URL is used more than once in 'environments' - ngrok documentation

What does ERR_NGROK_SHIP_APP_ENVIRONMENT_URL_DUPLICATED mean?

ngrok returns ERR_NGROK_SHIP_APP_ENVIRONMENT_URL_DUPLICATED with this message:

Environment URL <URL> is used more than once in 'environments'.

Where can I get more help with ERR_NGROK_SHIP_APP_ENVIRONMENT_URL_DUPLICATED?

Email support@ngrok.com and include the error code.