This was true for OWL-1, but is changed in OWL-2 (see: http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/#Metamodeling ; http://www.w3.org/TR/2009/REC-owl2-new-features-20091027/#F12:_Punning ).  OWL 2 DL still requires that Object and Data properties remain disjoint, as well as  Datatypes and Classes.    

Since the question can now be posed in OWL DL (one can assert EquivalentClasses and  DifferentIndividuals of the same URIS ). Of course, you can also assert that the two are sameAs, but without an assertion of  EquivalentClasses , you won't get the obvious entailments. 

Simon