I saw that they had their origins (axis’) in different places so for each I did a Structure/Center Axis/Center Axis To… then lined up both and made sure the “green” spline points were outside the “white” spline points. Then, because you had the axis’ on the left to clear the disk, I selected both the splines and moved their axis’ with the Object Axis Tool together.
To avoid that in the first place, if you were working in Illustrator just make both splines in the same document (just work on different layers) then they share the same origin (bottom-left corner in Illustrator). If working in C4D just make them both at the origin (0,0,0).