I did not understand the problem/question at first.
The "straight/even" brown does look a lot better. I think you could call it "done and good" for the backing now.
When putting a strip into a backing to make it larger - I have learned to deliberately offset if from the center - it's very difficult to line up something "exactly" with the top - and if it's deliberately off to one side, it's not annoying if it moves 1/2 inch (or more) one way or another.