Linq:
It own has the property of Distinct()
//Some data in Linq
List<data> list = new List<data>()
{
Name ="Swaraj Ambekar",
Name ="Swaraj Ambekar",
Name ="Swaraj Ambekar",
Name = "Forbes Technosys"
};
//Adding data source to combobox with linq
comboBox1.DataSource = list.Select(x => x.Name).Distinct().ToList();