Understanding Duplicates in Effect TS HashSet

{
        "_id": "HashSet",
        "values": [
          [
            "82",
            "blah"
          ],
          [
            "82",
            "blah"
          ]
        ]
      }

{
        "_id": "HashSet",
        "values": [
          [
            "82",
            "blah"
          ],
          [
            "82",
            "blah"
          ]
        ]
      }