APEX

I'm trying to parse JSON data into Interactive Grid through JavaScript for which I've used the following code, but it causes duplication of rows.

var widget   = apex.region('multiclauses').widget();
var grid    = widget.interactiveGrid('getViews','grid');  
var model    = grid.model;
var myJSONString = $v("G_STANDARD_AGENDA_JSON");
var myObject = JSON.parse(myJSONString);
model.clearData();
for ( var i = 0; i < myObject.length; i++)
{
  var obj = myObject[i];
  //insert new record on a model
  var myNewRecordId = model.insertNewRecord();
  //get the new record
  var myNewRecord = model.getRecord(myNewRecordId);
  //update record values
  model.setValue(myNewRecord, 'nd_description', obj.desc);
  model.setValue(myNewRecord, 'UW_CLAUSE_ID', obj.Clause_Code);
};