If you want to quote document A, but you find that document A has been quoted by document B, what you care about is whether if you quote document A, it will be considered as duplication and will be cited as the same document. In this case, as long as the language you write when you quote A is different from that described by B (not many consecutive words are the same, including tense voice), it is not your repetition, and there is no situation that papers can only be quoted once in the world. Otherwise, where do those highly cited papers come from?
2. You want to quote a part of document A, but in document A, this part also refers to document B. You are worried that when quoting A, it will be changed to be different from that of A, but it may be duplicated with B. The solution is to change the language description to be inconsistent with both A and B. Of course, the method of the pioneer has been described badly. Even if it is changed to flowers, there are estimates and repetitions. This kind of editor must also understand, and generally speaking, there is a periodical whose total repetition rate is not higher than a certain point, so it won't be copied, and it doesn't matter if it is repeated occasionally. In addition, you should also pay attention to the correct format of references and don't quote too many. Too many quotations will be regarded as plagiarism.