Merge PPT Files in PHP

$destinationPresentation = new Presentation("document1.ppt");
$sourcePresentation = new Presentation("document2.ppt");
try {
    $slideCount = java_values($sourcePresentation->getSlides()->size());

    for ($slideIndex = 0; $slideIndex < $slideCount; $slideIndex++) {
        $slide = $sourcePresentation->getSlides()->get_Item($slideIndex);
        $destinationPresentation->getSlides()->addClone($slide);
    }

    $destinationPresentation->save("merged.ppt", SaveFormat::Ppt);
} finally {
    $sourcePresentation->dispose();
    $destinationPresentation->dispose();
}