Reference for Menachot 48:10

אביי אמר אפילו נטמא אחד מהן נמי שניהם מצטרפין מ"ט כולהו בני ביקתא דהדדי נינהו

Perhaps it was prior to the midras uncleanness, so that it was a case of a graver uncleanness being imposed upon a lighter uncleanness.<span class="x" onmousemove="('comment',' And it is admitted by all that a thing which had contracted a lighter uncleanness (i.e., one which can only convey uncleanness to foodstuffs and liquids) cannot be so sated with uncleanness as to preclude any graver uncleanness (i.e., one which can convey uncleanness even to men and vessels) .');">⁵</span>

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