Why is there an error when issuing an SSL certificate?

Question

Nginx

There is a blockexample.com

server {
  listen 80;
  listen [::]:80;

  server_name example.online;

  root /home/example/deploy;
  index index.html;

  location / {
    try_files $uri $uri/ =404;
  }
}

server {
  listen 80;
  listen [::]:80;
  server_name www.example.online;
  return 301 $scheme://example.online$request_uri;
}

When I try to install the Lets Encrypt certificate, I get an error

Deployed Certificate to VirtualHost /etc/nginx/sites-enabled/example.online for example.online
nginx: [emerg] duplicate listen options for [::]:443 in /etc/nginx/sites-enabled/example.online:14
Rolling back to previous server configuration...
nginx restart failed:

Answer 1

fix it
combine everything into one block

Answer 2

The answer is here - https://serverfault.com/questions/258378/remove-ww...