You did not need the last section break at all.
I deleted it and changed the last section to landscape.
Inserting a next-page section break before the page you want landscape orientation and then changing the orientation of that section works does not add section breaks before and after. Selecting the page you want to be landscape and applying the orientation directly will insert two section breaks, one before and one after.
Sections / Headers and Footers in Microsoft Word 2007-2013