Excuse me, why do the stars in the old almanac have two versions on the same day?

Because there are two systems in the perpetual calendar, the first one is twenty-eight nights. Your previous one is based on the calculation of the road of justice and adopts the Taoist method. Which is the traditional almanac algorithm.

The latter is based on Twenty-seven Nights of Manjusri Bodhisattva, and it is the Yaosu Sutra which started in India. The latter algorithm is not popular in Chinese mainland, but the almanac compiled by Fu Zhengtang, a master of Feng Shui in Kong Xuan, mostly adopts the latter algorithm (because Li Juming also studies tantra). Because of Mr. Li's international influence, the latter algorithm is now widely circulated.

I hope the above answer has answered your question.