It is completely possible that someone has a similar last name and first initial. I wouldn't jump to that conclusion as I've seen it and my name is very unique, though the first three letters of my last name are not.

You can pull up your old res, just go to the manage reservations screen and you'll see 'Active, Past, Inactive, Cancelled'. Click on the past and pull it up. It should tell you what cabin you were seated in by the fare class.