Regarding the two days of Rosh Hashanah, we learned that Rav and Shmuel agree that an egg laid on the first day is prohibited on the second day.It was explained that this is because after the witnesses came late once, causing a confusion in the Shir, testimony was no longer accepted past Mincha. Thus if witnesses were to come late again, two days of Yom Tov would be kept while only the second day would be pronounced Yom Tov; thus lending a single extended Kedusha to both days. Rabbah then explained that from the time of Rabban Yochanan ben Zakkai, when it was no longer necessary to pronounce the second day Yom Tov on the first day, since he allowed accepting testimony all day following the destruction of the Beis Hamikdash, the law of the egg changed and it would be permitted on the second day.Rav Yosef argued that nothing changed in the time of Rabban Yochanan ben Zakkai since the law prohibiting the egg is considered a davar Sheb’minyan which requires an official decision to permit it and the decision of Rabban Yochanan ben Zakkai’s Sanhedrin was only made regarding testimony on the first day, not regarding the egg.
Rav Ada and Rav Shalman - both from Bei Kluchis [a place outside Eretz Yisroel]: The egg remains forbidden even after Rabban Yochanan ben Zakkai. We hope the Beis Hamikdash will be speedily rebuilt [and the old rule of not accepting testimony past Mincha will be restored] but people will say “we ate the egg last year, so we can eat it this year as well” - they won’t know that last year Rosh Hashanah was two separate Kedushas while this year both days have one Kedusha.
Challenge: If so we shouldn’t accept testimony past Mincha out of the fear that they will continue to do so once the Beis Hamikdash is rebuilt?
Resolution: Accepting testimony is in the capable hands of the Sanhedrin, but a decision on using the egg is made by every woman in her kitchen.
Rava: The egg remains forbidden even after Rabban Yochanan ben Zakkai’s Takanah. Rabban Yochanan ben Zakkai agrees that the second day remains holy - even when testimony is accepted late afternoon on the first day [thus: both days are one Kedusha].Rava (014): We follow Rav in these three things whether he is stringent or lenient: [1. Shabbos and Yom Tov which are contiguous (he is stringent, 013). 2. Two days of Yom Tov in Chutz La’Aretz (he is lenient, 015). 3. Two days of Rosh Hashanah (he is stringent, 016)]. 
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