Key thing is Job profile, make sure your offer letter includes the same description as your labor approval.
One of my friend had a same issue, he was questioned about his huge rise in the salary and they mentioned that its not the same job. So he has to prove that its the same job (which he did) and raise in salary was due to job location (NY, though he never changed his residence in NJ) and it also requires additional travel. His case was approved with AC21 inspite of employer revoked 140.