I'm able to create exactly same notifications - restriction should be put to API call and/or db-level.
PR #773
Metadata Update from @tkopecek: - Issue set to the milestone: 1.16
Commit 96a52c28 fixes this issue
Commit ad62cce5 fixes this issue
This issue has been migrated to Fedora Forge: https://forge.fedoraproject.org/koji/koji/issues/687
Please continue any further discussion there.