There is the same problem

There is the same problem with module for presta, but we can't also mix coupons together.

Please be more specific with what the problem is.

http://sodahome.net/en/

put something into the cart
and try use :

aaa code for coupon 1
bbb code for coupon 2
ccc for gift certificate

You will see you can't mix they together.

ok, I understand the problem now, you want the customer to be able to use multiple coupons. This is not enabled by default and in the backend you will need to go to awocoupon->configuration and set multiple coupons to yes.

niiice :)