Rabbi Yose says, "If that is what he intended from the outset, then, since it is impossible to utter two designations simultaneously, his declaration stands, but if he changed his mind in the process, it does not take effect." Rabbi Yose is also consistent with his view, except that here he explicitly states his reason.
If one tried to make a sacrifice exchange but did not use the right term, for example, if he said, "Let this be deconsecrated onto that," the exchange does not take place. However, if deconsecration was possible, such as when it was a sacrifice with a blemish, he effected the redemption. The new animal is consecrated, and if it is less expensive than the original one, he must add his money.
Art: Richard Ansdell - Feeding Goats in the Alhambra