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.
Positive Mitzvah 70
The Guilt-offering for questionable guilt
Leviticus 5:17 "Though he did not know it [if he sinned for sure], yet he is guilty, and shall bear his iniquity"
If a person is unsure if he committed any of the forty-three acts punishable by Karet (see above, Positive Mitzvah 69), he is commanded to bring this offering for his questionable guilt.