Trying to install second version on same server; moving domain

Hello. I’m trying to install a second version of Piwik on the same server but under a different domain name. The server is running nginx and php5-fpm. The original version works fine, however, when I attempt to run the second version, I’m seeing this in the error log:

2015/11/28 18:54:25 [error] 9043#9043: *4946 FastCGI sent in stderr: “PHP message: PHP Fatal error: Cannot redeclare class Piwik\Plugin\MetadataLoader in /vabt-sites/www.cheersva.org/public/piwik/core/Plugin/MetadataLoader.php on line 24
PHP message: PHP Fatal error: Cannot redeclare class Piwik\Config in /vabt-sites/www.cheersva.org/public/piwik/core/Config.php on line 42” while reading response header from upstream, client: 71.56.187.59, server: cheersva.org, request: “GET /piwik/ HTTP/1.1”, upstream: “fastcgi://unix:/var/run/php5-fpm-cheersva.sock:”, host: “www.cheersva.org

I’m using a separate config file as well as a separate database, however, I’m sharing the same DB username and password between the two.

I know it’s possible to run more than one website under a single version of Piwik, however, I’m retiring the original domain and wish to continue the stats under the new domain but still keep the original domain’s historical data.

Can anyone offer any insight?

Thanks much.

Regards,
Kory