Ohalos8: 6
שְׁתֵּי חָבִיּוֹת, וּבָהֶן כִּשְׁנֵי חֲצָיֵי זֵיתִים, מֻקָּפוֹת צָמִיד פָּתִיל, וּמֻנָּחוֹת בְּתוֹךְ הַבַּיִת, הֵן טְהוֹרוֹת, וְהַבַּיִת טָמֵא. נִפְתְּחָה אַחַת מֵהֶן, הִיא וְהַבַּיִת טְמֵאִים, וַחֲבֶרְתָּהּ טְהוֹרָה. וְכֵן שְׁנֵי חֲדָרִים שֶׁהֵן פְּתוּחִין לַבָּיִת.
[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.