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Docker build found duplicate stage names in the Dockerfile

DuplicateStageName

Docker build checks found more than one stage using the same stage name, which makes the Dockerfile ambiguous and harder to build correctly.

DuplicateStageNamebuild errors

Observed message

DuplicateStageName

Why it happens

  • Two multi-stage build sections reuse the same stage name.
  • A copied build stage was duplicated without renaming the alias.
  • The Dockerfile relies on stage aliases that are no longer unique after refactoring.

How to fix it

  1. Rename duplicate stage aliases so each build stage has a unique name.
  2. Update any COPY --from references to point at the renamed stage.
  3. Run the build check again to confirm no duplicate stage names remain.

Official reference

Docker Docs: Build checks

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