<p>The optimal solution is just to post a comment to the OP (and informing anyone who subsequently views the tread that it is a duplicate and) that cross-posting is frowned upon.  The OP should decide which site is more appropriate and delete the other.  If necessary, you can flag the moderators as well.  (Note that you cannot close a question on CV as a duplicate, if the potential duplicate is on another site.)  </p>
