A picture is worth a 1000 words :

So I fill both sides of the belt from my miners. I then want to evenly (from both side of the lane) put the iron one side of a new belt. Unfortunately, when the outside lane is full, it completely runs over the inside lane. It does the same thing with the copper. It might not be a big deal but it is annoying. The problem is that some of my miners are doing nothing while some are getting depleted. I know I could fix it with an inserter or two but I want to know if their is a solution with belt/splitters.
Thanks for any help.