That's exactly the brand I was referring to. In the trade they are known as sandwich box (those with kids will call them juice box). Not the sandwiches you eat, but the multilayers in the walls of the carton.
Still, I suspect your problem is that you weren't weighing the contents, but measuring them by liquid volume. If I was going to make something with tomatoes for dinner, I might be inclined to measure it out but I trust POMI pending any proof otherwise.