If someone says the wrong Haftarah or Shabbos (not just that they said the sephardi one b’makom the ashkanez one but a completely different Haftarah altogther.) Must they now say the right one when they realize their mistake?
This question involves a dispute among poskim.
If the first haftarah has been completed, and the berachos recited, Rav Shlomo Kluger (Shnos Chayim, Stam 10) writes that one has to read again with a berachah. He bases this ruling on the Shaarei Efraim (9:31). This is also ruled by the Eshel Avraham (Butshatch, 685).
However, the Levushei Mordechai (Kama, Orach Chaim 67) rules that one should not recite a berachah on reading the correct haftarah, also basing his ruling on the Shaarei Efraim (8:92) concerning somebody who read the weekly haftarah instead of that of Parashas Shekalim. In this case, the given ruling is that one should not recite the berachos when reading the correct reading, because a portion of the Navi was read, and the berachos of “who has chosen good prophets” were properly made.
The Shiyurei Taharah (5:10) goes a step further, and writes that when the wrong haftarah was read, even before the final set of berachos was recited, one does not have to read the right haftarah, because of torach ha-tzibbur (arguing that only in the case of Machar Ha-Chodesh, which must be read by dina de-Gemara, does one have to read the correct reading).
This extreme opinion, however, argues with other poskim (including the Kisei Eliyahu, and the poskim above), and one should therefore read the correct haftarah again, without a berachah.