These entries should not be there and are known as "GMST contamination". This issue occurs when you load only Morrowind.esm into the Construction Set. A good overview of the issue can be found on the UESP Wiki here. There are a number of ways to avoid / fix this.
The easiest way to prevent it is to load either Tribunal.esm or Bloodmoon.esm (or both) along with Morrowind.esm. This will avoid having these entries appear. (Note that if you load both Tribunal and Bloodmoon together, the CS will kick up a [rather large] number of warning messages about the previous / following string being different for certain dialogue entries during the load process. This is normal and is nothing to worry about.)
Another possibility is to use GMST Vaccine (download link here). This is useful if you want to make a mod that does not require the Tribunal and/or Bloodmoon expansions. Loading this .esp file into the CS along with Morrowind.esm will prevent this issue from happening. (Note that this .esp should be loaded in the Construction Set only -- do not load it when playing the game.)
You can also clean the mod (i.e. get rid of these entries) using tools such as TESTool and Tes3cmd. Once cleaned, use one of the above methods to prevent the problem from re-occuring the next time you edit your mod.
Happy modding!
