There were two 13th Amendments, with the first of the Thirteenth Amendments being adopted by the U.S. Congress in 1810.
Only formally approved articles become amendments. The ratified Article is the only one that matters.
Article. XIII. [Proposed 1865; Ratified 1865]
Section. 1. Neither slavery nor involuntary servitude, except as a punishment for crime whereof the party shall have been duly convicted, shall exist within the United States, or any place subject to their jurisdiction.
Section. 2. Congress shall have power to enforce this article by appropriate legislation.