This is not an error of duplication. The full-fledged version of this Mitzvah are many and change for those who are learning the one/three chapter a day. The Message for the day from "Bringing Heaven Down to Earth" at the end of this Mitzvah is different than that of yesterday.

Positive Mitzvah 105: Impurity caused by Discharge
Leviticus 15:16 "When a man discharges..."

The impurity of Shichvat Zerah may befall a man.

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Someone wrote that he had, in his administrative duties, taken an action that had fiercely angered one of his associates and turned him against him. The Rebbe replied: Bring into your heart a deep love of this man, and his anger will spontaneously disappear.

From: Bringing Heaven Down to Earth by Tzvi Freeman - tzvif@aol.com