Yes, it's common.
Don't be misled into thinking of your application and some other person's as being in a two-horse race. INZ are commonly receiving HUNDREDS of pieces of post every day. They are sorted by a staff of people (not just one, so there is not just one queue), directing them on to another staff of clerks to look them over. This is why just two items in that great sea of paperwork don't necessarily appear to be neck and neck.