A. Here’s the background. Jews in Israel dance with the Torah on the 8th night and day of the holiday. Jews in the Diaspora dance with the Torah on the 9th night and day of the holiday. The Ari’zal of Tzfat instituted “Hakafot Shniyot” – 2nd set of Hakafot after the holiday ended in Israel (on the night after the 8th day) to symbolize solidarity and unity with the Jews in the Diaspora. This custom became most famous in Kfar Chabad and is now popular all over Israel. In return, some Jews of the Diaspora instituted a Hakafot dance on Shmini Atzeret night in solidarity with the Jews in Israel. Being that Diapsora 8th night and Israel’s 9th night are symbols of solidarity and not Halachicly mandated, they are only done once – at night.