From what I've seen on here (although I can't speak from personal experience since I only used UWorld), a discrepancy between UWorld and Kaplan Qbank scores is normal. I used only UWorld, and though my score did loosely trend upwards, my scores were all over the place. My highest score was 78% and lowest was probably 50%, and I was hitting down to the 50's even in the week before my exam - my average over 3 weeks with about 50% complete was 60%.
Do yourself a favor and do *NOT* gauge your progress by UWorld scores. I am very suspicious that they may not correlate well with actual exam scores, even though I consider UWorld to be excellent preparation for the test. Also, I don't think the 150 questions are entirely representative of real boards questions. Take an NBME if you want to check your progress and estimate your score.
