Just mount two spindles and two parts?
Aw c'mon! That's too easy! There has to be a better way:
Seriously, I love the idea of two spindles for certain jobs, and this spindle is certainly cheap enough. Heck, I could probably fit 4 of 'em on my IH Mill! They scarcely cost more than the collet fixtures shown in my snapshot either.
Best,
BW