I know I've mentioned it before but I used to work for a time in a university admissions department and while it wasnt Oxford or similar, they absolutely can tell multiple applications from the same people, generally systems match applications up by name, date of birth etc so duplicates (over multiple years) are picked up. Also names and situations are easily remembered and discussed. Same with the admissions tutors for the course.
The old days of league tables and reputations as being important are slowly dieing. Employability, industry links etc are now taking over. Plus being happy where you study. The top universities do not necessarily offer the best route to employment (depending on courses). If anything the old universities are more stuck in the traditional academic study which doesn't translate to real world skills employers look for. Theory is all very well, but it has to be applied. Obviously something like English Literature which has less real world application probably doesnt factor employability as much