This article shows you how to export and import annotations (ink, line, rect, ellipse, note) from a page to another.

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//get first page
Page page = m_doc.GetPage0();
page.ObjsStart();
//get last added annotation
Annotation annotation = page.GetAnnot(page.GetAnnotCount()-1);
//save annotation data and export
float[] rect = annotation.GetRect();
byte[] data = annotation.Export();

//get second page
Page page1 = m_doc.GetPage(1);
//import annotation to the second page
page1.ImportAnnot(rect, data);