This might be slightly different. I have seen 2 different problems. I am not sure your problem is a variant of either of what I have seen or a 3rd yet similar problem.
Here are the two versions of the bug:
1) Add a product to the cart, two of that product are added to the cart and it states twice: “such & such” was added to your shopping cart.
2) On the back end configurable products show double on orders. My friend says it is the simple associated products. Not too big of a problem as the price is $0.
In both of these problems with v.184.108.40.206 they do not happen all the time and are not linked to specific problems, or we have not noticed any such patterns as of yet.