I might think that the beast tithe obtains with animals owned in partnership; it is, therefore, written "which shall be to you."
I might think to exclude brothers who acquired an estate and then divided it; it is, therefore, written "which shall be to you."
I might think that the beast tithe obtains with an orphan; it is, therefore, written "only" (connoting limitation).
(Devarim 12:27) "And you shall offer your burnt-offerings, the flesh and the blood": R. Yehoshua says: If there is no blood, there is no flesh; if there is no flesh, there is no blood. (i.e., if the flesh has become invalidated, the blood is not to be sprinkled; and if the blood has become invalidated, the sacrifice is invalidated.)