Should the primary navigation link be duplicated in the secondary navigation?

Consider this basic homepage.

If I click "About us", the page loads, I see content and also a secondary level navigation appears.

My question is whether I should have a page called "About us" as the first clickable-link in the secondary navigation or not.

I understand that if the secondary navigation appeared when I hovered over the first level, then it wouldn't be needed because I would be forced to pick a second level link, but in this situation when the secondary navigation appears only after the page loads, I'm not so sure what is best practice.