What I noticed is when there are two different products on a belt and it runs into a belt balancer, the contents of the belts are compactified on exit so the sides are all mixed up. If there are equal amount of items that enter they exit just fine but when one side is not fully saturated the output is a mess. Can you add an option to preserve the sides of a belt (keep what comes left to the left and what comes right - to the right). Of course this behavior has to be switchable.

This mixing up is intentionally. The Belt-Balancer was designed for mainBelts and other things, where you have a lot of the same item on multiple belts next to each other. When you want to have it side-based you can still use the normal splitters :)

Making that an option is a possibility. Unluckily, i dont really have time to implement that feature currently :(