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
""" Undo a reconciliation """
        if not self:
            return True
        rec_move_ids = self.env['account.partial.reconcile']
        for account_move_line in self:
            rec_move_ids += account_move_line.matched_debit_ids
            rec_move_ids += account_move_line.matched_credit_ids
        return rec_move_ids.unlink()
    
    
    
    
    @api.model
    def create(self, vals, apply_taxes=True):