Drush command terminated abnormally

2017-09-21 09:26:19

I'm using https://github.com/drupal-composer/drupal-project and get an error when starting drush:

[~/public_html/drupal]# alias drush="~/.composer/vendor/bin/drush"

[~/public_html/drupal]# drush

[error] Drush command terminated abnormally due to an unrecoverable error.

Error: Cannot declare class Drush\Commands\DrushCommands, because the name is already in use in /home/myuser/.composer/vendor/drush/drush/src/Commands/DrushCommands.php, line 12

What am I missing oder messing up? Thanks!