[Deorum]

Well, ethics aside, I believe that the standard rule in
cardrooms is that anyone playing in a hand when his or
her hand reveals that there is a duplicated card in the
deck, and continues the action as normal, must forefit the
pot at a showdown. So in the example you have given, if
you held J [img]/images/graemlins/spade.gif[/img]J [img]/images/graemlins/club.gif[/img] and the J [img]/images/graemlins/spade.gif[/img] hit the river,
and your bet was called, you would lose the pot. Of course,
if you have absolutely no morals, this would purely be a
pot odds situation (basically a bluff, as you cannot win in
a showdown). However, I would hope that everyone with whom
I am playing would bring it up before the hand went any
further.