Find duplicates in List(Of String) in VB.NET

Question

I have a customers List(of String) on which I am trying to find the duplicate customers.

If Not customers.Count = customers.Distinct.ToList.Coun         


        

Answer 1

customers = customers.GroupBy(Function(m) m) _
                 .Where(Function(g) g.Count() > 1) _
                 .Select(Function(g) g.Key).ToList