AM2 temps, Brisbane 6000+

I think I've finally gotten temp readings that reflect what my temps should
be, 42c at idle never above 60c at full load.
I have Speedfan 4.38b reporting the cpu temp at the same temp as the bios,
while core temp 99.5 shows core 0 and core 1 as about 4c higher.

My question: Should the core temps be a bit warmer than the reported CPU
temps, or should I adjust them down 4c to reflect the bios?

Another question: I noticed that the core that is working at a higher rate
is 2c cooler than the more benign core, is this an indication of unevenly
applied thermal grease?

TIA, TonyK