Can I combine two PDFs in PDFCreator?
No, the application doesn't allow you to combine to PDFs. This option is available in another application called PDF Architect. The Creator version is used to create PDF files using the virtual printer when Print is accessed.
Download PDF Architect using the following link: http://download.pdfforge.org/download/pdfcreator/PDFCreator-stable
To merge multiple PDF files, go to Create PDF section then press on Combine.