Hi, I have also faced this problem.
When I did my first GMAT Prep exam, I scored a 700 (Q49, V37). Last week, I took a
MGMAT CAT and scored 720 (Q49, V39).
Yesterday, I took the Veritas free test and scored an overall 700, even though my section scores were Q49 V42.
Wherever I have read, these raw scores indicate 740-750 range score. So, I don't know what is wrong with the Veritas system; because a difference of 10 points can still be chalked up to different algorithms, but a difference of 50 points makes a world of difference!
Cheers!