Check Duplicate Value in Multidimensional Array

var arr = [];
var result = [];

var frequency = arr.reduce(function (seen, currentItem) {
 if (currentItem in seen) {
  seen[currentItem] = seen[currentItem] + 1;
 } else { seen[currentItem] = 1; }
  return seen;
 }, {});

for (var key in frequency) {
 if (frequency[key] > 1) {
  result.push(key.split(',').map(function (currentItem) {
   return currentItem;
  }));
 }
}