Ohalos7: 6
הָאִשָּׁה שֶׁהִיא מְקַשָׁה לֵילֵד, מְחַתְּכִין אֶת הַוָּלָד בְּמֵעֶיהָ וּמוֹצִיאִין אוֹתוֹ אֵבָרִים אֵבָרִים, מִפְּנֵי שֶׁחַיֶּיהָ קוֹדְמִין לְחַיָּיו. יָצָא רֻבּוֹ, אֵין נוֹגְעִין בּוֹ, שֶׁאֵין דּוֹחִין נֶפֶשׁ מִפְּנֵי נָפֶשׁ.
[If] two sealed barrels, each containing a [piece of corpse] the size of half an olive, are located inside a house, [the barrels] remain tahor, but the house becomes tamei. [If] one of [the barrels] was opened, [that barrel] and the room are tamei, [but the other barrel] remains tahor. A similar [ruling] applies to two chambers that open into a room.