Homepage

DuplicateYAMLKey

Last edit: Aug 16, 2026

DuplicateYAMLKey

Severity: warning | Type: YAML

This check reports a key that appears more than once in the same YAML mapping.

The file still deploys. YAML keeps the last value, so the earlier one is silently discarded — which is why this is easy to miss: nothing fails, a translation or a schema property simply has a value you did not intend.

Examples

✗ Incorrect Code Example (Avoid using this):

en:
  greeting: Hi
  greeting: Hello

greeting is defined twice. The file deploys, greeting resolves to Hello, and Hi is discarded without a warning from the platform.

✓ Correct Code Example (Use this instead):

en:
  greeting: Hallo
  farewell: Tschuss

Keys that look different but are the same

platformOS reads YAML 1.1 (Ruby's Psych), which resolves several unquoted scalars to the same value. These are one key, not two:

fr:
  yes: Oui
  true: Vrai

Under YAML 1.1 yes and true are both the boolean true, so the second entry overwrites the first. The same applies to no/false, on/off, and to numeric forms such as 014 and 12 (the first is octal).

Quote a key you mean literally:

fr:
  "yes": Oui
  "true": Vrai

Look-alike detection is not exhaustive, so this check finding nothing does not prove two keys are distinct. A repeat of the same spelling is always reported.

Configuration

The default configuration for this check:

DuplicateYAMLKey:
  enabled: true
  severity: warning

Disabling This Check

Disabling this check is not recommended. It reports a value that is being thrown away, which no other check or platform error will tell you about.

Resources

Questions?

We are always happy to help with any questions you may have.

contact us