changelog duplicated entry across two releases, release notes broken

TL;DR

Delete the duplicated entry from the release where it does not belong, fix the tag range that generated the overlap, and republish the notes. Duplicates happen when a generation range overlaps the previous release's range - a retag, a moved tag, or generating from HEAD with no floor. Regenerate from strict tag-to-tag ranges going forward.

The error

changelog duplicated entry across two releases, release notes broken

Steps

1. List the tags and the ranges used: git tag --sort=-v:refname | head -8. Expected: you see which two releases share commits.
2. Compare each release's notes against git log OLD_TAG..NEW_TAG --oneline for both releases. Expected: you identify the commits appearing in both notes.
3. Decide where the entry belongs - the release that actually shipped the change - and delete it from the other release's notes. Expected: the change is documented exactly once.
4. If the notes are generated, fix the range inputs (previous tag and current tag) so the ranges are adjacent, not overlapping. Expected: regenerating produces no duplicates.
5. Republish the corrected release notes. Expected: each entry appears under exactly one version.

Use this when

• The same changelog entry appears under two different versions.
• Release notes were regenerated after a retag and gained duplicates.
• Reviewers flag repeated entries in the notes.

Not for this skill when

• The entry legitimately applies to two releases (a backported fix) - label it as a backport instead of deleting it.
• The duplication is within one release's notes - that is a generation bug, not a range overlap.
• You are merging two changelogs from different branches - that is a merge, not a range fix.

Variant phrasings

duplicate entries in release notes

Same problem, reported without mentioning the changelog. Same fix.

changelog entry appears twice

Same. Find the overlapping range.

release notes list the same change in two versions

Same, with the version detail spelled out. Same fix.

Why it happens

Changelog generators work on commit ranges, and ranges are only as correct as their endpoints. A tag moved after the fact, a release cut from the wrong branch, or a "generate from last release" heuristic that picks the wrong base all produce overlapping ranges. The generator then faithfully includes the shared commits in both releases.

Edge cases

• Backports: a fix shipped in v1.4.1 and also in v2.0 deserves an entry in both, marked as a backport. Do not "fix" this by deleting one.
• Deleted and recreated tags: the notes generated against the old tag position keep the old range. Regenerate after moving a tag.
• Auto-generated notes on some hosts use the previous tag as the base. If the previous release was deleted, the base falls back further and duplicates appear. Recreate or correct the base tag.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_cGX0K1orV2smX2YrOYG1zg