Friend is applying same course at the same college, we both do the same subjects

As for everything in life, there will always be someone better than you, and someone worse than you. It just so happens that one of those supposedly 'better' people went to the same place you did; it would be no different if they had gone to another school. That said, they might be 'better' on paper, but you might be significantly better at interviews or admissions tests, or have a better personal statement.
Regardless, you should ignore comparisons. Colleges admit more than one person, and there's no reason you couldn't both get in. When I went for my interview, I knew well that my grades (especially my GCSEs) were on the low end. But I didn't care, I had nothing to lose, so I did really well in my interview and got an offer. Stay focussed on your own performance, and good luck

There is absolutely no "hidden quota" that prevents colleges from making offers to more than one person from the same school for the same course. You'd be evaluated and compared to them as though they were any other candidate.

The only reason why it's sometimes advised against for more than one person to do this is because if one of you gets in and the other doesn't then you're likely to see it as some sort of "proof" that the other person is better than you, which isn't necessarily the case - sometimes the university is just looking for different things.

Edit: in addition, last year 2 people in my year both applied for biological natsci at Newnham and they both got interviews. (It did turn out that only one got an offer but that would certainly have been merit-based not because of any kind of quota).

So really the only possible setback is the emotional aspect in that I might know one of the people who 'beat' me for a place or vice-versa, and that is assuming the worst anyway.