2.  Single gpu works ok. But soon as you mutithread it on single gpu or single thread on multiple gpus, it will spit out "duplicate shares" everytime share is found.  and banned.  Perhaps, internal checker for duplicates isn't working as intended.  Even on single threaded gpu, it will spit out duplicates share if difficulty is low enough.  i.e. when dev donate mode starts, half the shares are rejected/briefly banned because it connects to low difficulty port.