Al-Infitar · Al-Inshiqaq

Both describe the sky splitting open — 82:1 uses 'infatarat' while 84:1 uses 'inshaqqat' — two verbs from different roots with overlapping meaning.

At-Takwir · Al-Infitar

Both describe the seas at the Last Day but 81:6 says 'sujjirat' (set ablaze) while 82:3 says 'fujjirat' (made to burst forth) — same root structure, different verb.

Al-Infitar · Al-Mutaffifin

Both state 'inna al-abrar la fi na'im' (the righteous will indeed be in bliss) in identical wording across Al-Infitar and Al-Mutaffifin.