Duplicate or Clone example to have less calls

clone.cs

using System;


class Program
{
    static void Main(string[] args)
    {
        var c = new Curve();
        var cc = c.Clone(); //cc is Curve

        var pc = new PolylineCurve();
        var pcc = pc.Clone(); //pcc is PolylineCurve
        var pccl = ((ICloneable)pcc).Clone();  //pccl is PolylineCurve but typed object

        var lc = new LineCurve();
        var lcc = lc.Clone(); //lcc is LineCurve

        PolylineCurve hc = new LineCurve();
        var hcc = hc.Clone(); //hcc is LineCurve but typed PolylineCurve
    }
}

class Curve : ICloneable
{
    protected virtual Curve DuplicateInternal()
    {
        return new Curve();
    }

    public Curve Clone() //Clone, could also be called Duplicate
    {
        return DuplicateInternal();
    }
    object ICloneable.Clone() //implicit interface implementation
    {
        return DuplicateInternal();
    }
}

class PolylineCurve : Curve
{
    protected override Curve DuplicateInternal()
    {
        return new PolylineCurve();
    }

    public new PolylineCurve Clone() //hiding lower method, here to provide convenient return type
    {
        return (PolylineCurve)DuplicateInternal();
    }
}

class LineCurve : PolylineCurve
{
    protected override Curve DuplicateInternal()
    {
        return new LineCurve(); 
    }

    public new LineCurve Clone() //same, hiding lower method for convenient return type
    {
        return (LineCurve)DuplicateInternal();
    }
}