DuplicateStageName

Output

Duplicate stage name 'foo-base', stage names should be unique

Defining multiple stages with the same name results in an error because the builder is unable to uniquely resolve the stage name reference.

❌ Bad: builder is declared as a stage name twice.

FROM debian:latest AS builder
RUN apt-get update; apt-get install -y curl

FROM golang:latest AS builder

✅ Good: stages have unique names.

FROM debian:latest AS deb-builder
RUN apt-get update; apt-get install -y curl

FROM golang:latest AS go-builder