Reported distance between the boundary lines is 2.25" and the reported width of the pair of Splines is 2.2512341459", even though the reported distance between the middle nodes is 2.25". Don't know how one could draw these entities as Splines and have them come out exactly correct without rather laborious post-editing. BUT it's pretty easy to make them as Beziers. After creating the Bezier by snapping on the three defining points, select it with the Edit tool and place the green rotation handles of the middle node directly on the boundary line (using "N" SEKE). I drew one Bezier this way and then mirror-copied it, and the reported width of the pair is precisely equal to the distance between the boundary lines.