Customer charged twice - no order created

[Tirips]

Hi,

 

I sell downloadable products.

For the first two orders I did not have automated the file sending (I do not know if it makes a difference for my problem).
On the following two commands, my customers were debited twice a few minutes apart and the cart remained pending.

I guess seeing no validation they pressed the button again ...

Help, how to make the cart behing an order after the payment?

 

Prestashop 1.5.6.2

PayPal 3.7.2