This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Yes you can use the same statement object, after all it is just as instance of class Connection. And with that instance you are invoking the method executeUpdate(). If it behaves differently then the basic OO Concepts itself is incorrect