Midrasz do Kapłańska 14:22

7) "the slaughtered bird" (hashchutah"): slaughtered through shechitah, and not through melikah ("pinching"). (What is the intent of this [of the apparently superfluous word "shechutah"])? I might think (without "hashchutah") that it follows that since the leper's amendment within (the sanctuary [viz. Vayikra 14:22]) is through birds, and his amendment outside (the sanctuary, i.e., our instance) is through birds — Just as his amendment within is through melikah, so his amendment outside is through melikah; it must, therefore be written "hashchutah," and not hamelukah." "the (blood of) the slaughtered bird over the living water (in the vessel)": not "the earthen vessel over the living water."

7) (Vayikra 14:22) ("And two turtle-doves or two young pigeons, such as his means suffice for; and one shall be a sin-offering, and the other, a burnt-offering.") "And two turtle-doves or two young pigeons": He brings two and not four.

8) (Why is a verse needed for this?) Does it not follow (that he should bring only two, viz.: He (a leper) brings what he can afford, and a woman after childbirth brings what she can afford. Just as she brings one (bird) for one (beast), so he brings one for one.