Is it possible to install multiple instances of openproject on one server?

Configuration
Debian 8
Current package installation of OpenProject with Apache as reverse proxy to Unicorn and Unicorn as application server

The package installation works fine for one instance, but as soon as a second instance is installed on the server, some configuration (which?) is overwritten and only the second instance is accessible via Apache.

This is the specification of etc/apache2/sites-enabled/openproject:

Include /etc/openproject/addons/apache2/includes/server/00_repositories_perl.conf


<VirtualHost 127.0.0.1:80>
  ServerName localhost

  # Include the repoman configuration in order
  # to access the repository from localhost
  Include /var/www/html/A/etc/openproject/addons/apache2/includes/vhost/repoman_svn_wrapper.conf
  Include /var/www/html/B/etc/openproject/addons/apache2/includes/vhost/repoman_svn_wrapper.conf
</VirtualHost>


<VirtualHost *:80>

    DocumentRoot /var/www/html

    ProxyRequests off

    Include /var/www/html/A/etc/openproject/addons/apache2/includes/vhost/*.conf
    Include /var/www/html/B/etc/openproject/addons/apache2/includes/vhost/*.conf


    # Can't use Location block since it would overshadow all the other proxypass directives on CentOS
    ProxyPass /A/ http://127.0.0.1:6000/A/ retry=0
    ProxyPassReverse /A/ http://127.0.0.1:6000/A/
    ProxyPass /B/ http://127.0.0.1:6000/B/ retry=0
    ProxyPassReverse /B/ http://127.0.0.1:6000/B/
</VirtualHost>

While Https://exampleserver/B works fine, Https://exampleserver/A returns “Not found /A/” (obviously an answer from Unicorn)

Thank you very much for your answer