What is the halacha if one does not make a bracha on a certain mitzva while someone else does - should the one who doesn't answer amen? For example - Sefardim don't make a bracha on Hallel on Rosh Chodesh while Ashkenazim do, should a Sefardi answer amen to the bracha of the Ashkenazi?
The Mishna Berura [Biyur Halacha 215 at the end] says .... yes. Rav Ovadiah says ..... no [Masa Ovadia page 23].
