Two Products instead of One gets added to cart


I have had several occurrences where there have been abandon carts and looking at them, I see two of the same item in the cart. Because of the type of product, there should not be two.

I just followed a previous customer through a new purchase (first time she used my cs-cart), while I was on the phone. She added the product to the cart and then was surprised and said there were two added, and she did not add two. For her, it was easy to fix, just change quantity to 1 and click update in the cart. I have no idea why this occasionally happens, and has nothing to do with the product, since it is with different products. I can not reproduce this myself. I know the customer was using IE 7.0. Not sure about the others, since they just left.

Has anyone seen this happen?

I am using version 2.1.1.

This is one of those things that you pull your hair out since you can’t reproduce it yourself, but you see it happen to others.