I can't say I remember if this crashes Poser for me or not, but then I try to avoid loading two instances of a figure with lights parented. Even if Poser does not crash, It seems to get confused by having the same light loaded twice, for one thing the intensity of the light is likly to double. I have a feeling that Poser actually does load two lights, it's just that they both have the same name, so they can't be differentiated. Do the lights use 'parent' or 'smartparent' statements, if it's 'smartparent' then you could try changing it to normal 'parent'.