GMAT Premium Online -- Wildly Differing Scores

Hi, I have recently taken two CATs as part of the premium online program, which in general, has been very helpful. The first time I took the test I received a 640 (62% Quant, 85% Verbal percentile) (26/37 Quant, 35/41 Verbal). The second time I took the CAT, which was today, I received a 750 (99% Qu...