anons, what does thekaisoo unnir mean by "동기"? (context: "As for Kyungsoo, because he came to SM on the same day as Luhan, he seems to really think “highly” of that because he excitedly told the fans about how they’re 동기’s.")

i looked it up in google translator and it give me "motive" or "reason". maybe he means they were destined to be in the same group?