Cut the same path with a change in Z axis

I am thinking of adding a Z axis to my setup.
I am a bit confused as to how to set up a cut, say a simple circle, that would have the first cut at Z=0
and the second cut done at Z - 2mm.
I do not have Z turned on in my setup. If I activate the Z axis, do I get some additional settings in the cut window?
Or do you lay a second circle on top of the first and assign a new color or layer to it?