CPUA is operating well above normal G5 temps. CPUB is doing better, but is still looking pretty toasty for its joint efforts in sending a measily email there in that peak. 40-50 with the odd peak to low- or mid-60s in semi-stressed operation would be normal. Hit the high 60s or low 70s with a G5 processor and you start to feel like you are on a runway getting ready for take-off.
Heatsink compound: In my experience, the G5 is really, really sensitive to heatsink compound quality and application methods, so this may help to explain the two graphs. As has been suggested, reapplication and even experimentation might therefore be useful. You might eventually need to run it on reduced power in the energy settings, though, as the dual 2.7 really is meant to have more aggressive cooling than air provides.
Overall, I think the slower G5s (1.8, 2.0 and 2.3) are the definite picks of the G5 litter as they run cooler and are in that sense so much more serviceable.