Where did you get the idea of cascading the 0.5 woofer's inductor to get the roll-off you wanted (and is there an easy way to see what's going on with the 0.5 woofer's output/response if it's cascaded with the 1.0 woofer?
Somebody on Mad mentioned cascading the woofers like that. If you wanted to isolate it, you could take a measurement with both, reverse the polarity of one, and take another measurement with both, and then do some math.