Aspose.Word InsertDocument lead to Section type Changed

Use the Api DocumentBuilder.InsertDocument(Document srcDoc, ImportFormatMode importFormatMode) to insert file into the other file ,but the section type ( from SectionBreakNewPage
to SectionBreakContinuous)changed

here is my demo (7.7 MB)

You have encountered the expected behavior of Aspose.Words. If you insert a document using MS Word you will get the same result.
If you need to retain sections as in the source document, you can consider using AppendDocument method instead of InsertDocument.