This error is telling you that you forgot to update your listening address. You likely have another pool configuration pointing to the same address.
For example, name1.conf is pointing to:
listen = 127.0.0.1:9000
And, name2.conf is pointing to:
listen = 127.0.0.1:9000
Simply update the port on one of the configurations and restart PHP-FPM. For instance, name2.conf could listen on:
listen = 127.0.0.1:9001
Restart:
systemctl restart php7.2-fpm.service