I wasn't able to make an account on the bug tracker. But I'm not sure if I would consider this a true bug anyway, more like just a mistake by Bethesda.
I mainly play SSE these days, but this is present in both versions. I'll point to the Oldrim mod, Whiterun texture memory usage reduction by DDVIL. DDVIL found this problem and tested it out. Please read that mod page for a very thorough description.
To summarize: there are two exact copies of the wrstonefloor texture, 01 and 02. 02 is the primary texture for almost all of Whiterun, except for a small part on a single mesh -- wrgreathouseplatform02.nif -- where 01 is used, causing unneeded VRAM usage. Fixing this only entails pointing the texture path to 02.
I'm posting this here because someone in the mod comments suggested that this would be a good thing for USLEP/USSEP, and I agreed, so here I am.