Having multiple students using the same quotes within their essays is not subject to plagiarism. This is because quotes themselves are not subject to plagiarism. They represent material that you are meant to effectively incorporate in your responses, should your aim be to perform well in your exams. It would therefore be normal for the same quotes to appear in multiple essays. This is similar to maths and science subjects, where students who correctly answer a question will likely have written similar (if not the same things) as working out in response to the question.
Additionally, even having the same analytical basis for the quotes that appear in different essays may not constitute plagiarism. Plagiarism is suspected and detected when a significant percentage of your response (including both quotes and analysis) is written in exactly the same way as one or more responses from other students (which also implies following an identical order/sequence).
Since you completed Business Studies, consider Section IV, for which you are required to incorporate relevant case study material to support your major points (and therefore provide a good quality response). There will likely be instances of students using the same case studies (a normal occurrence), which also suggests that this doesn't constitute plagiarism, as with the case of English.
I hope this helps!
