Origin unclear. The 二 (two) component hints at the meaning, conveying "second" or "again". The other component seems to depict a fish, similar to 冓, but its purpose is unclear.
again, twice, re-; again; once more; re-; second; another; then (after sth, and not until then); no matter how ... (followed by an adjective or verb, and then (usually) 也[yě] or 都[dōu] for emphasis)