The function gluPerspective() can be used to set near Z and far Z clipping planes.
I want to draw a scene clipped at a certain far Z plane, and draw another scene beyond this Z plane. Is it possible to do this clipping twice per frame?
There's no reason you shouldn't be able to do this.
Simply setup the first perspective, draw the first scene and then setup the second perspective and draw the seconds scene, all within the drawing of the same frame.
This is generally referred to as multi-pass rendering.