Custom properties of component are not duplicated

Hi,
I’m trying to create camera spline just for exercise.For the purpose I create camera spline (inherited from spline + addition property of type FInterpCurveVector) and CameraSplineVisualizer which is copy/paste of SplineVisualizer with few modifications. When I try to modify the spline the editor duplicate this spline and replace it with the copy (I don’t know why) And new copied spline have no properly copied custom property from the original spline.
Sorry for bad English.