Yoast/wordpress-seo — pull request #1733 by ramiy (2014-11-08 11:57:05+00:00)
Title: Merge similar translation strings

we use "Page Not Found" in "inc/class-wpseo-options.php:1547"
and
we use "Page not found" in "frontend/class-frontend.php:452"

If merged those two similar string, we will make it easier for the translations teams and decrease the .MO/.PO file size.