Whenever the customer makes an online payment, there is a problem many times that when the order is accepted and assigned to the delivery boy from the admin level, then after a while the status of the order changes and says that the order is placed. And when again accepting the order and assigning it to the delivery boy, the error states that the order is already accepted.
Earlier this problem used to come when we used to process the order by manually approving the online payment. After that I have integrated the "webhook" then the payment does not have to be approved manually but many times the problem mentioned above has to be faced.