To be fair, the stated aim was to keep the close up view good, while improving the distant scenery, and you can see that if you look at a tree nearby with a mountain in the background, but yes, this glitch, and the middle distance scenery tiling, certainly show it's tweaked, not new.
I wonder at what point, if ever, Bethesda will take a step back and agree it's time for a completely new engine... like they did back when they started working on Morrowind. I mean, it's not that big of a deal, now. Many engines carry traces of code from the engines they descended from... such as how you'll find a lot of Carmack's own coding in plenty of engines that supposedly branched off years ago. However, there will come a point when having remnants of Morrowind's coding in Bethesda's engine just won't be good enough, I imagine. It's only been 9 years, so that time isn't quite now, certainly, and after extensively modifying the engine as they just did, I imagine they'll use it for at least one more game, so perhaps for a Fallout 4 on the next console generation... but then what?