Are you talking about questions from OG being repeated on the real GMAT? If so, that is FALSE. The OG questions are official GMAT questions but retired. No way would they publish those to give away their test. You may get conceptually similar questions but not the exact same questions.
Yes, in fact what really changes is the shape but the main essence of questions still are the same. Eg: Paul eats 6 apples that costed him 25 cents. How much did he spend? can be changed in shape: Mary spent 1.50 dollars buying apples. If each apple costed her 25 cents how many did she eat?
So, as I thought this is a demystified assumption.