Hello Lyn,
QuickBooks does not enter transactions into batches - as soon as the invoice is completed it is posted and the general ledger (and all other accounts) are updated. You would have the same effect in Adagio if you created a new batch and entered each invoice into its own batch and posted the batch right away before entering the next invoice. Adagio does not let you post the same invoice number from the same vendor as this is almost always a duplicate entry. It only checks against invoices that are posted though. If the invoice has been entered twice, then just delete the duplicate. If not, then change the invoice number slightly to remove hte duplicate condition.
Two people can be entering invoices into Payables into different batches. There is a brief period when a new batch is being created that others cannot create another batch. It shouldn't "miss" a batch number though in this condition. I'll try and duplicate the issue here - thanks for bringing it to our attention.