I'm pretty sure that the dual 1.42 runs hotter than the dual 1.0. That is probably why Apple put a different copper heatsink on the 1.42. I'm not positive though.
My stock cooling 1.42ghz overclocked to 1.58ghz runs at 50c most of the time with light load. My point is it's fine running at 60c, it's not going to hurt it.