ParaView: How to decide which contour filter is on top?

I load two data files into paraview and use on both one contour filter. The resulting contour lines overlap. What I want and tried is the following:

1. load data file 1 into paraview, apply contour filter 1 on it.
2. load data file 2 into paraview and apply contour filter 2 on it.

Now I would expect that the contour filter 2 is on top of the first one at the overlapping area. But this is not the case.

Contour filter 2 contains only the black line. The first contour filter contains all the others. In the image the green-yellow-ish contour line is on top of the black one from filter 2.

Hopefully someone can help me. Thank you!

ParaView mostly relies on distance from the camera to determine what objects are rendered "on top". Probably the best way to make sure that the lines of one of the objects are rendered over the other is to displace one or both in the z direction. You can do that by modifying the Translation under the Transforming parameters of the display properties. I see in your screenshot that you have a 2D projection, so shifting the data in the Z direction should have no visible effect other than the distance to the camera.

You can achieve the same effect using the Transform filter.