What is the ruling if the parties disagree on which specific item was pledged?

Primary text

If the pledgor states, 'I pledged this slave,' and the pledgee states, 'Rather, it is this maid,' the slave is released from the pledge because the pledgee has confessed that the slave was not the object of the pledge. Furthermore, the pledgor swears that he did not pledge the maid, and thus the maid is also released from the pledge.