set up Crossfire a few minutes ago, ran WEI expecting it to be 7.9... but my graphics dropped from 7.7 to 6.0

granted, one card is a 6850 and the other is a 6870, but 6850/6870 are crossfireable so I should in theory reap the an increase in performance, not a decrease. I understand my 6870 is going to down clock to my 6850's settings, but I should still have a dual 6850 in that instance. I understand further more that WEI is really a set of numbers that are meaningless except for bragging rights essentially, but why did it drop?
defies logic....
and one more question. If I OC my 6850 to the factory settins og my 6870 that will run the 6850 at those settings and it would be like running 2 6850's to a degree, correct?