بسم الله الرحمن الرحيم
According to the preferred saying of Hanafi Fiqh, the time of Asr starts when the shade of each thing becomes two mithl other than its original shade. The time of Zuhr ends after mithlain (two mithl) and the Asr time starts. According to Shafi’i Fiqh, the time of Asr starts after mithl awwal. Imam Abu Yusuf and Imam Muhammad also have the same opinion as of Imam Shafi’i. If you have offered Asr salah as per Shafi’i time then it is not necessary to re-offer it. However, if there are more than one Hanafi people then you should permanently try to offer Asr salah as per Hanafi time with separate jamah.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.