Mishnayos Nazir Perek 3 Mishnah 7

In a case of one who had two sets of witnesses testifying about him that he had taken a vow of naziriteship for a certain period, and these witnesses testify that he took a vow of naziriteship for two terms, and these witnesses testify that he took a vow of naziriteship for five terms. Beit Shammai say: The testimony is divided, i.e., the testimonies contradict each other, and since the testimonies are in conflict they are both rejected entirely and there is no naziriteship here at all. And Beit Hillel say: The testimonies are not completely in conflict with each other, as two terms are included in five terms, and the unanimous testimony, that he is a nazirite for two terms, is accepted.

מִי שֶׁהָיוּ שְׁתֵּי כִתֵּי עֵדִים מְעִידוֹת אוֹתוֹ, אֵלּוּ מְעִידִים שֶׁנָּזַר שְׁתַּיִם, וְאֵלּוּ מְעִידִים שֶׁנָּזַר חָמֵשׁ, בֵּית שַׁמַּאי אוֹמְרִים, נֶחְלְקָה הָעֵדוּת וְאֵין כָּאן נְזִירוּת. וּבֵית הִלֵּל אוֹמְרִים, יֵשׁ בִּכְלָל חָמֵשׁ שְׁתַּיִם, שֶׁיְּהֵא נָזִיר שְׁתָּיִם: