The Gemmora quotes Reb Yehuda in the name of Shmuel, If starts Davening, Shemona Esray, and then he realizes that he has already davened he must stop where he is. The gemmorah later quotes another Reb Yehuda in the name of Shmuel that says if one enters a shul and he finds the tzibbur davening, then IF he can say something "new" in his tefilloh then he should daven again.
The gemmorah then goes on to say "TZERICHAH" Both cases are needed. and it explains why.
OUR (My Chavrusah at night and with the daf) question is: This Tzericha seems unlike any other Tzericha in Shas. The reason is that these two quotes of Reb Yehuda in the name of Shmuel seemingly are two different topics, without being at all reptitive, Whiscj is usually the case when the Gemorah says Tzerichah.
Are we missing something?
Thanks SO much
Yosey, it's true that the difference between the statements of Rav Yehudah seems obvious, but I think that subject of the Gemara's discussion is saying Shemoneh Esreh a second time. The Gemara considers it a "Chidush" that it is not permitted to pray Shemoneh Esreh twice. The fact that it is indeed not permitted is apparently the main point of Rav Yehudah's two statements. It is true that the first is dealing with a person who has already said twice half of SE, while the second is dealing with a person who wants to begin his second SE -- but isn't that the Gemara's logic in the conclusion of the Tzerichesa?