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 212: To Be Fruitful and Multiply
Genesis 1:28 "Be fruitful and multiply"

HaShem created the world for people to live in.

He wants the Jewish nation to grow and expand, ensuring the future of many generations of people to follow the Torah.

This Positive Mitzvah commands us to have children.

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A meditation for when things get rough: The world was brought into being with Goodness. And the ultimate good for Man is that he should not be shamed, but feel as a partner in the fulfillment of the Divine Plan. Free bread is to us bread of shame -- such is the nature of Man. That is why nothing good comes without toil. And according to the toil, can be known the harvest that will be reaped in the end.

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