G2.0-beta2 0.9.16 Fatal error: Cannot redeclare class matrix

Upgrading the Gallery Core Module
Your Gallery Core Module is up to date!

Currently installed 0.9.16
[Continue to Step 4]

= YES

= http://localhost/gallery2/upgrade/index.php?step=4

Fatal error: Cannot redeclare class matrixlayout in /home/gallery/public_html/gallery/layouts/gallery/layout.inc on line 34

Well, if you are up-to-date, then the link [Continue to Step 4] should not appear. ;-)

if (isset($_POST['confirm'])) {
/*
* Do the upgrade in bootstrap mode so that we avoid going to the
* database for anything that's not vital.
*/
$ret = $core->installOrUpgrade(true, $template);
if ($ret->isSuccess()) {
list ($ret, $ignored) = $core->activate();
if ($ret->isSuccess()) {
$storage =& $gallery->getStorage();
$ret = $storage->commitTransaction();
}
}
if ($ret->isError()) {
$templateData['stackTrace'] = $ret->getAsHtml();
$templateData['debug'] = $gallery->getDebugBuffer();
$templateData['bodyFile'] = 'UpgradeCoreModuleError.html';
} else {
$templateData['bodyFile'] = 'UpgradeCoreModuleSuccess.html';
$this->setComplete(true);
}
} else {
if ($core->getVersion() != $versions['core']) {
$templateData['bodyFile'] = 'UpgradeCoreModuleRequest.html';
$this->setComplete(false);
} else {
$templateData['bodyFile'] = 'UpgradeCoreModuleUpToDate.html';
$this->setComplete(true);
}
}

$template->hideStatusBlock();
$template->renderBodyAndFooter($templateData);
}
}

you can use the upgrader to upgrade modules too, so we allow you to step all the way through even if nothing needs upgrading.

Please fill out the support template. Also include what G2 version you originally installed, and what version you were upgrading from when this error first occurred. Is your site working ok now? With what version?

Gallery URL (optional):
Gallery version:
Webserver (with version):
Datatabase (with version):
PHP version (eg 4.2.1):
phpinfo URL (optional):
Graphics Toolkit(s):
Operating system:
Web browser/version:
G1 version (for migration bugs):