Merge PPSM Files in C#

using var firstPresentation = new Presentation("first.ppsm");
using var secondPresentation = new Presentation("second.ppsm");
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.ppsm", SaveFormat.Ppsm);