samba - Jul 2004 - Could two DOMAINS of the same SID exsits on the same network?

Greetings!
        Few general questions:
        1. Could I vampire from a BDC instead of PDC, does a BDC have 
everything that a PDC has?
        2. After vampiring successfully from a PDC to samba-3 BDC, could I 
promote this samba-3 BDC to a PDC of a new  domain NEWDM, would this new 
domain co-existing with the old domain in the same network? I am worring 
that the two domains have exact same information, e,g, domain SIDs. Would 
that affect anything? 
        Thanks!
-- Kang Sun