Sum of discounts different than in paypal (PS 1.7.5.1)

[mikelfdez85]

I have a Prestashop 1.7.5.1 installed and I see that when there's more than one discount it don't add up. For example, if there're 2 discounts of 10%, Prestashop doesn't make a total discount of 20%, Prestashop makes a 10% discount and then again a 10% discount, which isn't the same.

However, in the breakdown of discounts the invoice shows them as if you were making 20% in total, but in the subtotals, the sum of the discounts does not match the sum of these 2 breakdown amounts, it is very rare.

And if it's a Paypal order and I download the Paypal invoice, it makes a total of 20% discount.

Do you know if this is a bug or that it just does it by default?

I attach a screenshot of the invoice.

Thanks a lot