function removeInstalled(&$params)
    {
        if (!isset($params[0])) {
            return;
        }

        $options = $params[0]->_downloader->getOptions();
        if (!isset($options['downloadonly'])) {
            foreach ($params as $i => $param) {
                $package = $param->getPackage();
                $channel = $param->getChannel();
                // remove self if already installed with this version
                // this does not need any pecl magic - we only remove exact matches
                if ($param->_installRegistry->packageExists($package, $channel)) {
                    $packageVersion = $param->_installRegistry->packageInfo($package, 'version', $channel);
                    if (version_compare($packageVersion, $param->getVersion(), '==')) {
                        if (!isset($options['force'])) {
                            $info = $param->getParsedPackage();
                            unset($info['version']);
                            unset($info['state']);
                            if (!isset($options['soft'])) {
                                $param->_downloader->log(1, 'Skipping package "' .
                                    $param->getShortName() .
                                    '", already installed as version ' . $packageVersion);
                            }
                            $params[$i] = false;
                        }
                    } elseif (!isset($options['force']) && !isset($options['upgrade']) &&
                          !isset($options['soft'])) {
                        $info = $param->getParsedPackage();
                        $param->_downloader->log(1, 'Skipping package "' .
                            $param->getShortName() .
                            '", already installed as version ' . $packageVersion);
                        $params[$i] = false;
                    }
                }
            }
        }

        PEAR_Downloader_Package::removeDuplicates($params);
    }