Some rabbbonim have publicly paskened hat Bet Shemesh might have the status of a walled city and while we continue to celebrate on the 14th of Adar, this year on Wednesday night and Thursday, but we should also celebrate due to significant uncertainty on the 15th of Adar like a walled city by reading the megilla again and performing the other basic mitzvos on Thursday night and Friday.

Other rabbonim have said that in Bet Shemesh we only celebrate on the 14th and not the 15th. The uncertainty about Yermuth is questionable enough that we do not need to be concerned.

Both have sources and valid reasons for their positions.

Rabbi Yaakov Haber, rav of KSY (Kehillat Shivtei Yeshurun) in RBS A, asked noted posek Rav Asher Weiss his psak on the matter. I would note that I heard Rav Haber last Shabbos say that there is no need to celebrate on the 15th at all in Bet Shemesh and he quoted form the Mishna Brura as his source for his decision.

Rav Asher Weiss wrote a psak in return saying that there is no need to read the megilla on the 15th in Bet Shemesh. In his letter (below) he details all the doubts and questions involved when combined leave significant reason to not bother with the 15th and not to even be considered a possibility.

source: Kikar