Hi chaim_9068,
Thank you for reaching out.
There is no default option to combine PDFs in this way. However, you may try the following workaround.
- First, combine both the PDFs using the Combine Files tool.
Once done, you can use the organize pages tool to set the pages in the order you wish them to appear after merging. For example, page 1 of the English PDF and then page 1 of the Spanish PDF, respectively.
- Then, use the Print icon and select Adobe PDF as the printer.
- Under "Page Sizing & Handling" in the Print window, select the Multiple tab.
- For pages per sheet, select custom from the drop-down menu and set it to 1 by 2 in the following boxes.
- Set the page order and orientation as required.
- Click on the Print button at the bottom of the Print window.
See if that works.

Let us know if that helps.
Thanks,
Meenakshi