Mishnayos Yevamos Perek 13 Mishnah 10

If one widow was halakhically competent and one widow was a deaf-mute, and the yavam engaged in intercourse with the halakhically competent woman and then engaged in intercourse with the deaf-mute, or if his brother then engaged in intercourse with the deaf-mute, the yavam or his brother did not disqualify the halakhically competent woman from staying married. Since the yavam consummated the levirate marriage with her first, the levirate bond was entirely dissolved and the intercourse with the deaf-mute, though forbidden, had no effect. If the yavam engaged in intercourse with the deaf-mute and then engaged in intercourse with the halakhically competent woman, or if his brother engaged in intercourse with the halakhically competent woman, the yavam or his brother disqualified the deaf-mute from staying married. Consummation of the levirate marriage with the deaf-mute creates only a partial acquisition that does not fully dissolve the levirate bond.

פִּקַּחַת וְחֵרֶשֶׁת, בָּא יָבָם עַל הַפִּקַּחַת, וְחָזַר וּבָא עַל הַחֵרֶשֶׁת, אוֹ שֶׁבָּא אָחִיו עַל הַחֵרֶשֶׁת, לֹא פָסַל אֶת הַפִּקַּחַת. בָּא יָבָם עַל הַחֵרֶשֶׁת וְחָזַר וּבָא עַל הַפִּקַּחַת, אוֹ שֶׁבָּא אָחִיו עַל הַפִּקַּחַת, פָּסַל אֶת הַחֵרֶשֶׁת: