Check out this wonderful post on understanding HashSet
http://dotnetcodr.com/2014/01/08/using-hashset-in-net-to-allow-unique-values-only/
http://alicebobandmallory.com/articles/2012/10/18/merge-collections-without-duplicates-in-c
The Message box will show the count as 2.
HashSet will remove the duplicate entry.
Bye
