Impacted versions: 9.0, 9.0 enterprise

Steps to reproduce:
On current runbot duplicate any posted journal entry which is balanced

Current behavior:
Error message "Cannot create unbalanced entry" is shown

Expected behavior:
New Journal entry is created in state 'draft'

Video/Screenshot link (optional):
![selection_268](https://cloud.githubusercontent.com/assets/14974044/15007437/41f45a56-11d9-11e6-84f3-b297befaa521.png)

addons/account/models/account_move.py
for move in self:
            lock_date = max(move.company_id.period_lock_date, move.company_id.fiscalyear_lock_date)
            if self.user_has_groups('account.group_account_manager'):
                lock_date = move.company_id.fiscalyear_lock_date
            if move.date <= lock_date:
                if self.user_has_groups('account.group_account_manager'):
                    message = _("You cannot add/modify entries prior to and inclusive of the lock date %s") % (lock_date)
                else:
                    message = _("You cannot add/modify entries prior to and inclusive of the lock date %s. Check the company settings or ask someone with the 'Adviser' role") % (lock_date)
                raise UserError(message)
        return True
    @api.multi
    def assert_balanced(self):
        if not self.ids:
            return True
        prec = self.env['decimal.precision'].precision_get('Account')
        self._cr.execute("""\
            SELECT      move_id
            FROM        account_move_line
            WHERE       move_id in %s
            GROUP BY    move_id
            HAVING      abs(sum(debit) - sum(credit)) > %s
            """, (tuple(self.ids), 10 ** (-max(5, prec))))
        if len(self._cr.fetchall()) != 0:
            raise UserError(_("Cannot create unbalanced journal entry."))
        return True
    @api.multi
    def reverse_moves(self, date=None, journal_id=None):