Integrate validation of unique names that are being assigned through the UniqueName property of the GanttBoundColumn class to prevent the same assigned two times.

E.g.

RadGantt myGantt = new RadGantt();
GanttBoundColumn boundColumn = new GanttBoundColumn();
boundColumn.UniqueName = "Unique";
myGantt.Columns.Add(boundColumn);

GanttBoundColumn boundColumn2 = new GanttBoundColumn();
boundColumn.UniqueName = "Unique"; // this should be validated
myGantt.Columns.Add(boundColumn2);