Multiple Isosurfaces from same data values

Greetings Bill and List.

I have a scalar mapping of value->Display.IsoContour and together with a
ContourWidget it gives a nice isosurface in the display.  What I was
wondering was how can add another IsoSurface with a lower alpha value
(on just the second surface) using the same values from the data set
(rather than making a duplicate set and creating new scalar mappings)?
Is this possible?

Thanks,
Matt Leonard