title: Merge PDF files from multiple folders with same filename
body: <p>I am looking to merge PDF files from two separate folders into a third folder, based on file name.</p>
  
  <p>Directory structure:</p>
  
  <pre><code>FOLDER_1 = File set #1.
  FOLDER_2 = File set #2.
  MERGED_PDFS = Output of merged files.
  </code></pre>
  
  <p>FOLDER_1 contains a set of PDF files which could be named with any combination of letters, numbers and allowed symbols.</p>
  
  <p>FOLDER_2 contains a set of PDFs with the exact same names as FOLDER_1. The data on these sheets is different. The files from FOLDER_2 need to be inserted into the files from FOLDER_1, at the end of the file.</p>
  
  <p>The output of this merged file will be placed in the MERGED_PDFs folder, retaining the name used to match the files in FOLDER_1 and FOLDER_2.</p>
  
  <p>Example:</p>
  
  <pre><code>FOLDER_1: R000135322.PDF
  FOLDER_2: R000135322.PDF
  MERGED_PDFS: R000135322.PDF
  (MERGED_PDFS contains a merged PDF from FOLDER_1 &amp; FOLDER_2, with the PDF from FOLDER_2 being placed at the end of the PDF in FOLDER_1.
  </code></pre>
  
  <p>I saw some similar examples of this being done with PDFtk, but unsure how to edit to get my expected output.</p>
  
  <p>Thanks</p>