Add multiple namespacs with same address to XDocument

I need to add multiple namespaces to the xdocument with same address (C#)

<root xmlns:f="urn://xml.voodoo.net/vd/formating-1.0" xmlns="urn://xml.voodoo.net/vd/formating-1.0">
 <a:something>stuff and more stuff</a开发者_JAVA百科:something>
</root>

if i add using the below code.. it shows only xmlns:f

XNamespace defaultNS = "urn://xml.voodoo.net/vd/formating-1.0";
XNamespace f = "urn://xml.voodoo.net/vd/formating-1.0";


XElement rootElement = new XElement(defaultNS + "root",
new XAttribute(XNamespace.Xmlns + "f", f.NamespaceName),

how to show 2 namespaces?? is it even possible?

var doc = new XDocument(
    new XElement(defaultNS + "root",

        new XAttribute(XNamespace.Xmlns + "f", defaultNS),
        new XAttribute("xmlns", defaultNS),
        new XElement(defaultNS + "something",
            new XAttribute(XNamespace.Xmlns + "f", defaultNS), "stuff and more stuff")
            )
    );

Desired output:

<root xmlns:f="urn://xml.voodoo.net/vd/formating-1.0" xmlns="urn://xml.voodoo.net/vd/formating-1.0">
  <f:something xmlns:f="urn://xml.voodoo.net/vd/formating-1.0">stuff and more stuff</f:something>
</root>

Your XML example is incorrect, the 'f' namespace is not used, whereas there is an 'a' namespace present.

Your C# code does not match your XML, it creates an element with an attribute.

Anyhow, a namespace definitions within an XML document only makes sense if you actually use it. If you create an XML document via C# code, it will generate XML which is semantically correct, yet might not match the syntax of your example.