Incorrect behaviour of suspend/resume JTA Transaction

XAConnection pool defined in JBoss (see attachment).
JDBC Connection is resued across TransactionManager suspend/resume calls with second transaction rolled back:

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UserTransaction userTransaction = (UserTransaction)Locator.lookup("java:comp/UserTransaction");
TransactionManager tm = (TransactionManager)Locator.lookup("java:/TransactionManager");
DataSource dataSource = Locator.getDataSource("java:/TXDataSource");

userTransaction.begin();

Connection connection = dataSource.getConnection();

// insert record in DB
doSmth(connection, "A");

// suspend
Transaction transaction = tm.suspend();

// start another transaction
userTransaction.begin();

doSmth(connection, "B");

userTransaction.rollback();

// resume first tx
tm.resume(transaction);

userTransaction.commit();

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// insert method
private void doSmth(Connection conn, String value) throws SQLException {
PreparedStatement ps = null;
try

{ ps = conn.prepareStatement("insert into a(a_name) values(?)"); ps.setString(1, value); ps.executeUpdate(); }

finally

{ Locator.close(ps); }

}
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Expected result: 1 rows in a table after execution of the above code. Actual result in JBoss: 2 rows.
Same test works as expected in WebLogic 8.1.4