Hi greetings

The National testing agency is giving different questions in different shifts of JEE main exam because if JEE main question gets repeated then those students home later appear for the exam can already ask the questions from their peers and the exam will be quiet easy for those therefore to keep in mind this fact the question for each shift is different but you don't need to worry regarding difficulty level of the paper because the normalisation will be done separately for each shifts.

This helps all the best.