stamp.insertPage(1, LwgPageSize.A4);
over = stamp.getOverContent(1);
over.beginText();
over.setFontAndSize(bf, 18);
over.showTextAligned(LwgElement.ALIGN_LEFT, "DUPLICATE OF AN EXISTING PDF DOCUMENT", 30, 600, 0);
over.endText();
// adding a page from another document
PdfReader reader2 = new PdfReader("SimpleAnnotations1.pdf");
under = stamp.getUnderContent(1);
under.addTemplate(stamp.getImportedPage(reader2, 3), 1, 0, 0, 1, 0, 0);
// closing PdfStamper will generate the new PDF file