Commentary for Kiddushin 101:6

Hizkiyah and R. Yohanan were not arguing about Rabbah’s principle. They were arguing about how we interpret the person’s words when they were stated unclearly. If he clearly states that he only intends for forty to be sanctified, then they are sanctified, although we would not know which are sacred and which are not. If it sounds like he is trying to make all eighty sacred, then the statement definitely does not work because whatever cannot be done consecutively cannot be done simultaneously. The only issue is whether when he simply states that all 80 are being sacrificed we assume that he was taking responsibility that if some loaves were ruined, others would be sacred in its place, or whether he intended to actually dedicate eighty loaves.