Duplicating Word document using OpenXml and C#

Question

I am using Word and OpenXml to provide mail merge functionality in a C# ASP.NET web application:

1) A document is uploaded with a number of pre-defined strings for s

Answer 1

The original question was asked before a number of helpful features were added to the Open XML SDK. Nowadays, if you already have an opened WordprocessingDocument, you would simply clone the original document and perform whatever transformation on that clone.

// Say you have done this somewhere before you want to duplicate your document.
using WordprocessingDocument originalDoc = WordprocessingDocument.Open("original.docx", false);

// Then this is how you can clone the opened WordprocessingDocument.
using var newDoc = (WordprocessingDocument) originalDoc.Clone("copy.docx", true);

// Perform whatever transformation you want to do.
PerformTransformation(newDoc);

You can also clone on a Stream or Package. Overall, you have the following options:

OpenXmlPackage Clone()

OpenXmlPackage Clone(Stream stream)
OpenXmlPackage Clone(Stream stream, bool isEditable)
OpenXmlPackage Clone(Stream stream, bool isEditable, OpenSettings openSettings)

OpenXmlPackage Clone(string path)
OpenXmlPackage Clone(string path, bool isEditable)
OpenXmlPackage Clone(string path, bool isEditable, OpenSettings openSettings)

OpenXmlPackage Clone(Package package)
OpenXmlPackage Clone(Package package, OpenSettings openSettings)

Have a look at the Open XML SDK documentation for details on those methods.

Having said that, if you have not yet opened the WordprocessingDocument, there are at least faster ways to duplicate, or clone, the document. I've demonstrated this in my answer on the most efficient way to clone Office Open XML documents.