specialization question

One of our consultants has created a new domain specialization 
in which he specializes step.  He doesn't change the name.  

This works OK in the specialized topic DTD shell, but he runs 
into trouble when he tries to include this domain in the ditabase 
DTD shell.  The problem is that there are two different step 
elements, his from the domain and the regular one from task.  

If I were doing this, I'd probably use a new name for the
specialized element, but that isn't what this person wanted
to do.

Should it be possible to do what he wants to do?

paul