Hi Kalpana,
Thank you for your update.
Currently DocIO provide support for cloning and merging the entire content from source document (doc2.doc) to the destination document (doc1.doc) using ImportContent() method instead of cloning and merging each section. Please refer the code snippet from below illustrating the same. Try using the below code snippet and let us know if this helps you.
Code:
doc1.ImportContent(doc2);
Please refer the below UG link for more information
http://help.syncfusion.com/ug_93/Reporting/DocIO/ASP.NET/default.htm?turl=Documents%2F431cloningandmerging.htmPlease let us know if you have any questions.
Regards,
Poornima