ns1 and ns2 as namespace prefix in CXF 2.3.11

I am suing CXF 2.3.11.

Here is my package-info:

@javax.xml.bind.annotation.XmlSchema(namespace = "mynamespace",
elementFormDefault = javax.xml.bind.annotation.XmlNsForm.QUALIFIED)

I have small ping method in my rest web service. I have a similar method in
soap web service.

When I get a soap response back, all elements are prefixed with ns1.
In rest they are prefixed with ns2 and sometimes ns1.

Is there any reason behind this?