When you open a register on your computer, it will request the next invoice number from our servers and put this aside. When a sale is completed, the computer will use this reserved invoice number.
Reciept numbers can be duplicated here when the sale is not completed on this machine and the same register is opened on a different computer. This computer will also request the next invoice number from our servers and receive the same invoice number as the first computer if it is not used in a sale.
If you then complete the sale on this second computer and go back to the first machine at any time in the future, it will have saved this now duplicated invoice number.
Why does it save the next receipt number locally? It saves and reserves the receipt number like this in case Vend drops offline and it can't check in with the server to find the latest receipt sequence.
Lets look at an example situation where this duplicate can happen:
Lets say you've turned on your laptop, selected a register and opened the vend sell screen. At this stage Vend will have reserved the next receipt sequence for you. Instead of making a sale right a way however, you close this laptop and go to do something else.
In the meantime, you or your staff open up the same register on your desktop computer and head to the sell screen. This will also reserve the next receipt number in the sequence which, in this case, is the same as the first computer as no sale was made against it. You then go on to make a sale on your desktop computer here.
After a little while you decide to open up your laptop again and complete a sale on the sell screen that is still sitting open. This will use the same receipt number that was reserved earlier and create a duplicate receipt.
How can I avoid this from happening?
Below are a few tips on how to avoid duplicate receipt numbers going forward:
Only ever use one register per computer and not the same register for multiple computers. If you need to have more than one point of sale at any time, add a new register and use this register on a dedicated machine.
Make sure to reload the Sell Screen (or close and re-open your browser) whenever you switch between two different computers connected to the same Vend Register. This will make sure the Sell Screen has the most recent invoice number from the server.
Close your register from the computer it was opened on rather than from a seperate back office device.
Only use Vend in Chrome, in one browser tab at a time.