Jethro was called by 7 names in the Tanach. Rashi summarizes:
שֶׁבַע שֵׁמוֹת נִקְרְאוּ לוֹ: רְעוּאֵל, יֶתֶר, יִתְרוֹ, חוֹבָב, חֶבֶר, קֵינִי, פּוּטִיאֵל He was called by seven names: Reuel, Jether, Jethro, Chovav, Cheber, Keni and Putiel. [Rashi on Ex. 18:1]
The Sources elaborate:
1-He was called יֶתֶר Yeter (from יִתֵּר, “to add”) because he caused the addition of a Torah portion, Yitro (Ex. 18:1-20:23) and he was he was “abundant” (yiter) in good deeds.
2-Jethro, because when he converted to Judaism a letter (vav) was added to his name: יִתְרוֹ.
3-Chovav חוֹבָב, because he “loved” (חִבֵּב) God and the Torah [Mekhilta d'Rabbi Yishmael 18:1:2].
4-Reuel רְעוּאֵל: Torah says Reuel was Chovav’s father, but sometimes children call their grandfather “father”. [Sifrei Bamidbar 79, on Numbers 10:29]
5-Keni קֵינִי [in Judges 1:16], because he was “zealous”(kinei) for God and “acquired” (kanah) the Torah [Mekhilta Yitro 1].
6-Chever חֶבֶר [in Judges 4:11], because he was the “associate” of God.
7-Putiel פּוּטִיאֵל [in Ex. 6:25], because he had renounced idolatry (niftar). A different interpretation: “he fattened calves” (pittem) for idolatrous sacrifice. [Bava Batra 109b]
(1) However, Balak, Korach and Sarah have Torah portions named after them and their names were not changed. Also, (3), (5) and (6) are the same general idea. (2) and (7) are also the same idea.
Do the Sources discuss why there was a need for this proliferation of names, not emulated elsewhere?