$pdfDocs = array($filePath1,$filePath2);
        $pdfNew = new Zend_Pdf();
        foreach ($pdfDocs as $file) {
            $pdf = Zend_Pdf::load($file);
            $extractor = new Zend_Pdf_Resource_Extractor();
            foreach ($pdf->pages as $page) {
                $pdfExtract = $extractor->clonePage($page);
                $pdfNew->pages[] = $pdfExtract;
            }
        }

        $mergePdf = "mergefile.pdf";
        header('content-type:application/pdf');
        echo $pdfNew->render();
Zend 自带的库，好像只支持pdf1.4及以下版本pdf文件