Reference for Yevamot 46:12

ודוקא מיחלץ והדר יבומי אבל יבומי ברישא לא דקא פגע ביבמה לשוק:

and it was not stated 'and it was not known'<span class="x" onmousemove="('comment',' Which would have implied that the identity of the betrothed was never known. ');">³⁰</span> This proves it. What, then, does our Mishnah teach us?<span class="x" onmousemove="('comment',' If the betrothal was valid and the man does not know now whom he betrothed it is self-evident that both women must be divorced! ');">³¹</span>

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