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)

""" Create domain criteria that are relevant to manual reconciliation. """
        domain = ['&', ('reconciled', '=', False), ('account_id', '=', account_id)]
        if partner_id:
            domain = expression.AND([domain, [('partner_id', '=', partner_id)]])
        generic_domain = self.domain_move_lines_for_reconciliation(excluded_ids=excluded_ids, str=str)
        return expression.AND([generic_domain, domain])
    @api.model
    def get_move_lines_for_manual_reconciliation(self, account_id, partner_id=False, excluded_ids=None, str=False, offset=0, limit=None, target_currency_id=False):
        """ Returns unreconciled move lines for an account or a partner+account, formatted for the manual reconciliation widget """
        domain = self._domain_move_lines_for_manual_reconciliation(account_id, partner_id, excluded_ids, str)
        lines = self.search(domain, offset=offset, limit=limit, order="date_maturity asc, id asc")
        if target_currency_id:
            target_currency = self.env['res.currency'].browse(target_currency_id)
        else:
            account = self.env['account.account'].browse(account_id)
            target_currency = account.currency_id or account.company_id.currency_id
        return lines.prepare_move_lines_for_reconciliation_widget(target_currency=target_currency)
    @api.v7
    def prepare_move_lines_for_reconciliation_widget(self, cr, uid, line_ids, target_currency_id=False, context=None):
        recs = self.browse(cr, uid, line_ids, context)
        target_currency = target_currency_id and self.pool.get('res.currency').browse(cr, uid, target_currency_id, context=context) or False
        return AccountMoveLine.prepare_move_lines_for_reconciliation_widget(recs, target_currency=target_currency)
    @api.v8
    def prepare_move_lines_for_reconciliation_widget(self, target_currency=False, target_date=False):
        """ Returns move lines formatted for the manual/bank reconciliation widget
            :param target_currency: curreny you want the move line debit/credit converted into
            :param target_date: date to use for the monetary conversion
        """
        context = dict(self._context or {})
        ret = []