[FinalBuilder Professional Edition]
The PDF Merge Files action will merge two PDF files into a new single PDF File.

File 1, File 2 - The files to merge
Output File - the name of the new PDF file
Include Outlines - Include the outlines from the source files in the new PDF file
Include Form Fields -Include Form Fields from the source files in the new PDF file
Rename Likename Fields - Rename any field names which are the same in the two source files in the merged file.