Once the Ishraq time starts, is it permissible to pray Chasht salah after Ishraq salah?
بسم الله الرحمن الرحيم
Yes, it is lawful. The timing of both the salah is same.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.