The game does not have any mechanism to deal with this situation, so it randomly grabs the texture from one or the other BSA file. May is over and the Morrowind May Modathon 2020 celebrating the 18th anniversary of all-time classic TES III: Morrowind is coming to an end. Check you have 'ArchiveInvalidation' (AI) enabled. (Consider 'Lonesome Road' as an example of similar problems with any DLC.
