XML adds prefix on cloneNode

I'm doing some XML transformations with PHP.

I need to move some of the nodes inside of other new node. I'm creating a node array of all elements (cloneNode and then push to the array) that need to be moved, deleting them from the xml document, create a new element and after that re-inserting them. Everything looks perfect to the moment I have default prefix on my object. Here is simple example what's my input

<div class="my class">
    <myobject xmlns="someNameSpace" class="file">
        <mySubObject ......./>
    </myobject>
</div>

and the output is

<div class="my class">
    <default:myobject  xmlns="someNameSpace" class="file">
         <default:mySubObject ......./>
    </default:myobject>
</div>

"someNameSpace" is included in the master xmlns

 <xs:import namespace="someNameSpace" schemaLocation="path/to/the/someNameSpace.xsd" />

Have no idea how I can clean it up, or why I'm getting this "default" front of the "myobject"