Why does it say "Anochi Anochi"?
Rashi: I always erased your sins, and I do so also now.
Radak: This strengthens the matter. I pardoned the sins of Dor ha'Midbar, and I pardon your sins in every generation.
Malbim: Refer to 43:25:2:4.
Why does it say "Lema'ani"?
Rashi: It is not in your merit, and not due to the virtue of your fathers.
Radak: Lest My name be profaned through you, if I eradicate you.
Radak (24): According to Mishpat, I should have eradicated you immediately! I bore it for My sake, and not for yours; I will exact payment for your sins little by little.
Malbim: Korbanos are only for Shogeg. Then, it is as if the sinner helps erase them via his Korban. There is no Korban for Pesha'im; I alone erase them, for My sake, for I desire Chesed.
What is the meaning of "v'Chatosecha Lo Ezkor"?
Malbim: Do not say that a sinner helps to erase his Chet via his Korban. I do not pay attention to Shogeg sins! To Me, Mezid sins of rebellion are primary.