The short answer is no. The bar raiser and the hiring manager cannot be the same person.
The long answer is that it's complicated.
For the process to work, the recruiting manager who works with the candidate through the interview process must be different from the hiring manager. This ensures that two people are looking out for the company's best interest and that the candidate isn't being pushed through by someone who wants to fill a role.
The bar raiser is usually, but not always, someone different from the hiring manager. This helps to ensure that the candidate is being assessed against Amazon's high standards by someone who isn't personally invested in the outcome.