A family of Microsoft word processing software products for creating web, email, and print documents.
Insert a next page section break at the beginning of book one, to insert an empty page above book one.
Book one will now be section 2.
Go into the header of section 2 and click to deselect "Link to Previous" in the Navigation group of the Header & Footer tab of the ribbon.
Do the same for the footer of section 2.
You can then clear the header and footer of section 1 (the blank page at the start).
Similarly, insert a next page section break at the end of book one, and another one at the beginning of book two. This will create another empty page. The empty page will be section 3 and book two will be section 4.
Deselect "Link to Previous" for the header and footer of section 4, and then also for the header and footer of section 3.
You can then clear the header and footer of section 3 (the blank page between the books).