By activating the "payment shortcut module", you will be able to process fast payments (only with cash or card) on the same order.
First of all, you need to activate it. So, enter into your Back Office > Configuration > Your Modules > Payment and activate the module "payment shortcut", then return to your App and press refresh (on the top right).
Now, in the order screen you will have the option below to select twice cash or card and the whole order will be cashed automatically. 