Do same songs occurring on multiple releases require different ISRC codes?

No. The ISRC code for a song stays the same no matter what album this track occurs on. A new ISRC is required only if ANYTHING about the song changes (track length, title, audio mastering, etc.).

According to the ISRC Manual, a new ISRC must be issued when:

    • A sound recording is re-mixed or edited.
    • If a new fade changes the length of a track by more than 10 seconds.
    • Edits that change the length of a sound recording by more than 10 seconds (playing time is measured from the first recorded modulation to the last recorded modulation).
    • A previously released sound recording is partially used as part of a compilation.
    • A “full restoration” of a historical recording is performed by re-mastering, re-pitching, re-equalizing, de-noising or de-clicking a sound recording to meet contemporary quality standards. The registrant of the recording has discretion when making the determination between full re-mastering (sound restoration) and simple re-mastering (reproduction without sound restoration).