We are sorry for the inconvenience you’re experiencing right now because you cannot create multiple purchases at once with GoFood.
 

On the GoFood service, we have set the terms in limiting the number of purchases for ongoing bookings, the maximum number of purchases that can be created at the same time is 4 (four) purchases. 
 

If you get the notification, it happens because you are trying to create 5th purchase while the previous one is still ongoing.
But don't worry! You can still create another purchase after your previous one is completed by the driver.
 

Hope this information helps you.