Here are the steps to follow to copy a board to a new one:
Step 1. Go to the board you want to export
Step 2. Click on the clockwork icon (settings)
Step 3. Now click on "Export board"
Step 4. Select the "CSV" format and click on the “Export” button to download the CSV file
Step 5. Now go to the board you want to import the content into, after that click on the clockwork icon (settings)
Step 6. Find the "Import CSV" option
Step 7. Now click on “Upload file” to select the CSV file that you downloaded before
Final Step. The final step is to match all the columns from the CSV into the columns of the new board, after doing that click on "Import" to copy your board to a new one