The main impact creating the same invoice multiple times will be on your Accounts Receivable as it will have the same amount recorded 12 times, as the system will expect each amount to paid and closed in the invoice. Whether or not that is inflated to the business, that being said, when it comes to reconciliation, as long as you have the bank deposits to match against each invoice created, overall there is no issue with creating all these invoices. 

In regards to the dashboard graphs that display sales and expense you should rely more on the reports themselves to show the accurate amounts. The current design of the Dashboard graphs include all deposits to the bank account in the income balance. The system will record only the actual income assigned to the bank account.