xml2js is duplicating xml tags

Question

I am trying to add a record to my XML file.

Here is the original file

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<data>
  <bookings>
    <record>
      <user>1</user>
      <flight>1</flight>
    </record>
  </bookings>
</data>

Here is what I want

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<data>
  <bookings>
    <record>
      <user>1</user>
      <flight>1</flight>
    </record>
    <record>
      <user>2</user>
      <flight>2</flight>
    </record>
  </bookings>
</data>

Here is what is actually happening

<data>
  <bookings>
    <record>
      <user>1</user>
      <flight>1</flight>
    </record>
  </bookings>
  <bookings>
    <record>
      <user>2</user>
      <flight>2</flight>
    </record>
  </bookings>
</data>

You can see the bookings tag is getting duplicated.

Here is my code

    fs.readFile(filePath, 'utf8', (err, data) => {
        console.log('hey', data);
        // convert XML to JSON
        parseXml(data, function(err2, json) {
            if (err2) console.log(err2);

            json.data.bookings.push({
                "record": [
                    {
                        "user": [
                            userId
                        ],
                        "flight": [
                            flightId
                        ]
                    }
                ]
            }); 

            // create a new builder object and then convert
            // our json back to xml.
            var builder = new xml2js.Builder();
            var xml = builder.buildObject(json);
        
            fs.writeFile(filePath, xml, function(err, data) {
                if (err) console.log(err);
        
                return 'Your booking is complete'; 

            });
            });
    });

Any idea what's going on here?