Reference for Yevamot 74:19

ספק ובני יבם שבאו לחלוק בנכסי יבם לבתר דפלג יבם בנכסי מיתנא

while here both are doubtful!<span class="x" onmousemove="('comment',' He himself whose claim to heirship is certain is also in doubt as to who exactly his father was and by virtue of whose rights he is entitled to the estate. ');">³⁴</span> If, however, a case is to be compared to a Mishnah it is to the following: That of a 'doubtful son'<span class="x" onmousemove="('comment',' V. supra p. 236, n. 2. ');">³⁵</span>

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