Merging in multiple anchors results in validation error

[puco]

When using anchors and merging multiple anchors into the same object Visual Studio Code complains about invlid document.

Document:

.numbers: &numbers
  one: "1"
  two: "2"

.countries: &countries
  us: "United States"
  uk: "United Kingdom"

instance1:
  <<: *numbers
  <<: *countries
  something: "else"

Expected result: The document is valid

Actual result: Error in validating document

JS-YAML: duplicate key at line 10, column 3
JS-YAML: duplicate key at line 11, column 3