Hi, If you are still looking for a soltuion to this, you can try using the Checkout Guardian App, where in you can block all the orders based on the cart value. For Example we can set a rule to block checkout if the cart value is USD 0, which means a person wont be able to checkout if his cart value is 0. Apart from it it offer various conditions to block checkout from these fake orders.
You can have a look at it here Checkout Guardian App.