[TYPO3-commerce] Coupon extension - every visit increase the money amount reduction in the basket

[Christian]

Hello,
I have a strange behaviour with the extension "commerce coupons 0.2".
When I put a coupon in the basket, the coupon plugin show me that the 
coupon is valid and invit me to check the basket again so the 
###COUPON_VIEW### marker is filled in the commerce basket template.
The problem is that each time I visit my basket, the coupon value is 
multiplicated by the number of time I reload/visit my basket o_O
Anyone else encountered this problem ? I put the coupon plugin before or 
after the pi2 commerce plugin and it's the same behaviour. I also 
deactivated the hooks I created for commerce but nothing can solve this 
problem.

Thanks

Christian