Unit Storage input imbalance

Issue description

Two copper smelters feeding into one first level unit storage hub. The inputs are at different rates. Looking at the input side the left input is running much faster than the right input. the right smelter is always backed up while the left isn't.
This causes an imbalance in the amount of work each smelter has to do.
All unit storage inputs should input at the same rate
This applies to all siozes of unit hub.

Reproduction steps

Load attached save
find the copper smelters and watch

Game version and build number

v0.6.4d b347

Operating system

Windows

Attachments

What 12.save

What 12 fixed.save

That does not really work in that situation. if there is a problem with one smelter they both stop.

Is it not enough like this? There's only one conveyor at the exit anyway.

That is just avoiding the issue.

The logical thought would be; attaching two belts of the same speed to the two inputs of one storage would force those inputs to accept at the same rate. This is not happening.