Famous from the Han-dynasty 古诗十九首 ('Nineteen Old Poems'): 迢迢牵牛星,皎皎河汉女 — 'Far, far away the Cowherd Star, bright, bright the Maid of the Milky Way' — the canonical depiction of the Cowherd-and-Weaving-Maid legend. The doubled adjective is a classical poetic device for vividness.
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Distinctly literary. Modern prose uses the single character 皎 only in compounds like 皎洁 (jiǎojié, 'bright and clean'); the doubled form 皎皎 stays in poetry and lyrical writing.
