Under normal circumstances, novels with the same theme were not considered plagiarized. Because plagiarism refers to the repeated use of the same idea or work with similar plots, characters, theme, or structure. However, if the same or similar subject matter is used multiple times and there is a lack of ingenuity or innovation between these works, it may be considered plagiarism. If the same subject matter was used in different works and there was creativity or creativity between these works, then it was not plagiarism. However, if the same plot, characters, theme, or structure is used repeatedly in different works and there is a lack of creativity or innovation between these works, it may be considered plagiarism. Whether it was considered plagiarism depended on the specific circumstances of the work, including whether it was original or not, whether it was considered plagiarism in law, and so on. If you have any doubts about whether a novel of similar subject matter is plagiarized, you are advised to consult a professional lawyer.