dc and dcterms in the same schema

Hello! 

I am a bit new at this. I'm trying to construct a schema that would include
some elements of the simple dc and some elements of the dcterms, meaning
that it won't accept all the others. I have managed to do this, but when a
include some elements of the dcterms e.g. I have dc:title and
dcterms:alternative, it tells me that I violate the Unique Particle
Atribution rule. Is there any way to bypass this? And is this thinking
(including only some elements of the dc and dcterms) correct? Any help would
be deeply appreciated... 

Thank you in advance!

 Rania