How to finding duplicate elements in array

1. var counts = new Dictionary<int, int>();
2. int[] array = { 10, 5, 10, 2, 2, 3, 4, 5, 5, 6, 7, 8, 9, 11, 12, 12 };
3. for (int i = 0; i < array.Length; i++)
4. {
5. int currentVal = array[i];
6. if (counts.ContainsKey(currentVal))
7. counts[currentVal]++;
8. else
9. counts[currentVal] = 1;
10. }
11. foreach (var kvp in counts)
13. MessageBox.Show("\t\n " + kvp.Key + " occurs " + kvp.Value);