As you can see, the wording is rather different. The current one starts with "...you gain the endurance..." while the PDF I have is "...you can channel the endurance...", and some of the other wording also differs.
I guess they had two editions of this UA. Both what I downloaded and what they have up there now have the same name of 2017_01_UA_RangerRogue_0117JCMM.pdf.
I wonder if there are any other differences...
Horizon Walker looks exactly the same with an eyeball grep. I'm actually just looking for number of lines and spotchecking that each line on the page starts with the same word.
Rest of Primeval Guardian looks the same.
Scout looks the same.
So the PDFs are identical except that the wording in Ancient Fortitude varies in several places, but to the same mechanical effect except one version only allows it once per rest.