multiple add to cart and

[smpconseil]

Hello I have a problem
With the old version (1.1) I could easily put several "add to cart" with  quantity choice on my product. (See picture).
With version 2 I can not do it, I must definitely make a mistake with my custom fields? Or this feature is no longer supported?
Is a plugin for it?
In fact, in this case I want to put an extra option but does not increase with the number ordered. Let me explain the customer orders 10 items and there extra charge only on the first (manufacturing costs).
Excuse me for my bad english, I'm french.
Thank you for your help