TT #96 · Parshas Tazria · Aliyah 2 · Passuk 6
English: And the kohen shall see him on the seventh day a second time. And, behold! the lesion has become dimmer, and the lesion has not spread on the skin, the kohen shall pronounce him clean. It is a mispachath. He shall immerse his garments and become clean.
Chabad.org — Chumash, English translation + Rashi for Vayikra 13:6
Torah Temimah cites Sifra (Toras Kohanim) for the requirement that the same kohen examine the case at both examinations.
Sifra — Vayikra 13, Midrash Sefer
English: This teaches that the kohen who saw him the first time sees him the second time.
Textual derivation
The second examination is performed by the same kohen who conducted the first examination, preserving continuity of judgment.