Same result? Create a group of all the layers - put the mask that is currently on layer 1 on the GROUP. Change the groups blend mode to Normal. Now there are no clipping groups necessary and your curve will only affect the layers held within the group. If you want the curve to affect JUST layer 2, you can still create a clipping group there.
I will admit that once in a while I have needed stacked clipping groups, but there are always other, better ways to achieve the same result.
thanks for trying to find a workaround, but that won't do it ... if I remove the mask from layer 1, it doesn't have the correct shape for it's layer style (drop shadows, etc.) any more, for example.
Anyway, this is just a simple example. I've many times come across more complex layer configurations where stacked clipping masks would come in real handy. So I hope maybe the Adobe team will one day warm up to this idea ...