פירוש על קידושין 45:13

If we try to solve this last problem by positing that the slave can be redeemed even when others accept the document on his behalf, and also when he accepts the document, and that this mishnah teaches that it is to the slave’s advantage to go free (and thus others can receive his document), then we encounter the problem that both clauses say the same thing. So why teach them as independent clauses?