Yevamos13: 8
מִי שֶׁהָיָה נָשׂוּי לִשְׁתֵּי יְתוֹמוֹת קְטַנּוֹת, וָמֵת — בִּיאָתָהּ אוֹ חֲלִיצָתָהּ שֶׁל אַחַת מֵהֶן פּוֹטֶרֶת צָרָתָהּ. וְכֵן שְׁתֵּי חֵרְשׁוֹת.  קְטַנָּה וְחֵרֶשֶׁת — אֵין בִּיאַת אַחַת מֵהֶן פּוֹטֶרֶת צָרָתָהּ. פִּקַּחַת וְחֵרֶשֶׁת — בִּיאַת הַפִּקַּחַת פּוֹטֶרֶת אֶת הַחֵרֶשֶׁת, וְאֵין בִּיאַת הַחֵרֶשֶׁת פּוֹטֶרֶת אֶת הַפִּקַּחַת. גְּדוֹלָה וּקְטַנָּה — בִּיאַת הַגְּדוֹלָה פּוֹטֶרֶת אֶת הַקְּטַנָּה, וְאֵין בִּיאַת הַקְּטַנָּה פּוֹטֶרֶת אֶת הַגְּדוֹלָה.
[If] someone was married to two minor orphans and died, cohabitation or chalitzah with one of them releases her co-wife. So too, [in the case of] two deaf-mutes.  [If one was] a minor and [one was] a deaf-mute, cohabitation with one does not release her co-wife. [If one was] competent and [one was] a deaf-mute, cohabitation with the competent one releases the deaf-mute, but cohabitation with the deaf-mute does not release the competent one. [If one was] an adult and [one was] a minor, cohabitation with the adult releases the minor, but cohabitation with the minor does not release the adult.