Changing the unit name via the Editor's unit properties dialog box can result in the deletion of the original unit name and a duplication of the new name in the \text\EN\unit.txt file.
The following is an example of the covert changes made to the \text\EN\unit.txt file after I had:
1. Deleted the BB named "Conte di Cavour";
2. Changed the BB named "Andrea Doria" from "Andrea Doria" -> "Conte di Cavour";
As shown below, unexpectedly this change modified the BB's unit names list, by duplicating "Conte di Cavour" and removing "Andrea Doria" entirely.


Just because I change a unit name on the map does NOT mean I am done with that name and wish it removed!
In fact, I expect the name to continue to exist until I explicitly remove it from the unit's name list.