//Instantiate Presentation class that represents PPTX file
Presentation pres = new Presentation(dataPath + "presentation.pptx");

// Save presentation with chart
pres.save(dataPath + "Aspose-Duplicate.pptx", SaveFormat.Pptx);

String inputfilepath = dataPath + "presentation.pptx";

PresentationMLPackage presentationMLPackage = 
    (PresentationMLPackage)OpcPackage.load(new java.io.File(inputfilepath));

System.out.println("\n\n saving .. \n\n");
presentationMLPackage.save(new java.io.File(dataPath + "Pptx4j-Duplicate.pptx"));