Many POS providers and other restaurant related programs that receive invoice information from suppliers have developed programs that allow these invoices to be imported into accounting programs.
This is seen as a time saver as you don't need to re-enter the invoice into another system which eliminates double entry.
The problem I have found with systems like this is that they can not process all invoices, only beverage invoices in the case of POS or food invoices if its a food ordering program. You still need to manually process other invoices.
I also find that these systems generally do not check if an invoice is already in the accounting program which leads to duplicate invoices being processed and duplicate payments.
When we process bills, I prefer one system to process invoices. At Pacific Business Partners we use a system called Lightyear that automates bill processing. All bills go through this system and then into the accounting program. This helps eliminate duplicate processing.
Lightyear also integrates with some POS systems so that you can export invoice data out of Lightyear and then receive it into a POS system as a purchase order. It means that staff do not have to manually process a large purchase order into the POS and can just confirm numbers.
Lightyear also has a double approval process for all your invoices. Invoices need to be approved by 2 users before it is exported into the accounting system. As part of this approval there is a price checking feature so that you can compare invoice prices with price lists from your suppliers.
So if you want to ensure accuracy, accountability and no duplicates, then you should implement one system to take care of you invoice processing. Having many systems will only lead to more mistakes and frustration.