When I worked for Target, I worked overnights, so I know how this works. We were let out an hour "early" but we still got our 8 hours of pay. Or we were allowed to stay the extra hour and get paid for 9 hours. We never seemed to be on break during the "extra" hour.
In the spring, we'd actually work 7 hours but get paid for 8 hours and we still got all of the regular breaks.
No, we didn't take any product off the shelf (unless we were cleaning up overstock) and we didn't re-do anything.
I assume that Walmart does the same thing for its employees, but since I live in Arizona now, I wouldn't know.