BookMyShow — Same seats booked by different individuals

I had booked 6 tickets for Rocketry [7:20 p.m.] on 30/07/2022 in INOX ORION MALL, Gorakhpur through bookmyshow.
Seats were CL-D7, D8, D9, D10, D11, D12. Everything was fine until one man came along with his friend and showed their ticket for D8 and D9. HOW CAN TWO DIFFERENT PEOPLE BOOK SAME SEATS? How can the transaction system of bookmyshow be so inacuurate? If these types of errors continues, it will be discouraging for the viewers as someone else comes and claims the seat which is already booked by both different individuals.