Every CONSTRUCT is DISTINCT?

[I preface this with a "I don't want to delay anything even a little  
bit!" comment. I don't!]

<http://chatlogs.planetrdf.com/swig/2007-10-15#T14-35-05>

It seems to me that CONSTRUCT implicitly DISTINCTs. Is this true? It  
seems to me that there is room for a CONSTRUCT that had duplicate  
triples in it (for the usual reasons of streamability).

If there was I discussion about this point, and it's easy for someone  
to dig out, I would appreciate a pointer.

Cheers,
Bijan.