You only need one file, either TE_CityInteriorRetexture - Override or TE_CityInteriorRetexture - Hak.

Extract the Hak file into your Hak folder if you only want the override to effect 1 module.
Extract the Override file into your Override folder if you want all modules to use the retexture.

Email me at BridgetLGray@gmail.com if you have any questions :)