You can cite the same source twice. A professor will have a set number of how many different cites he/she wants, but otherwise yeah, using the same source twice cited the same is completly okay.

you actually have gone very far know that insight. you have come to the door where knowledge is not needed anymore so discard it. knowledge shows you the door for those who haven't seen, now discard knowledge and just walk through the door. after going through the door and you can acquire new knowledge by asking the source.

human knowledge and enlightened knowledge are on different levels. and there isn't a paradox if you have gone to the source.

it's like a magic trick. you have knowledge of the magic when shown, but after enlightenment, the magic turns into a trick. the magic trick is still there, you just see it as a trick after enlightenment.

good luck, forgetting everything is a lot tougher than you might think, but of course you have to discard this too. there are methods to help you.