Merge PPTX Files in C#

using var firstPresentation = new Presentation("first.pptx");
using var secondPresentation = new Presentation("second.pptx");
using var mergedPresentation = new Presentation();

mergedPresentation.Slides.RemoveAt(0);

foreach (var slide in firstPresentation.Slides)
{
    mergedPresentation.Slides.AddClone(slide);
}

foreach (var slide in secondPresentation.Slides)
{
    mergedPresentation.Slides.AddClone(slide);
}

mergedPresentation.Save("merged.pptx", SaveFormat.Pptx);