[MDEP-976] artifactId is not guaranteed to be globally unique

**[Gili](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=cowwoc)** opened **[MDEP-976](https://issues.apache.org/jira/browse/MDEP-976?redirect=false)** and commented

The copy-dependencies Mojo incorrectly assumes that a dependency's artifactId is globally unique. If a project depends on two different groupIds that happen to have the same artifactId then one dependency will overwrite the other.

Consider adding ${groupId} to the default output filename and/or add an option for doing so in case users wish to retain backwards compatibility.

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**Affects:** 3.8.1

**Remote Links:**
- [GitHub Pull Request #523
](https://github.com/apache/maven-dependency-plugin/pull/523)

Start by reviewing the copy-dependencies Mojo and the linked pull request #523. Reproduce the case with two dependencies sharing an artifactId but using different groupIds, then confirm that both outputs are retained while the requested backwards-compatibility behavior is preserved.

Written by the indexing model from the issue text.