Chain identifier should be blank not A: ATOM   2941 MG    MG A 365      48.079  -2.336  22.333  1.00 23.16      A   MG  
Chain identifier should be blank not B: ATOM   2971 MG    MG B 366      59.074  50.051  55.046  1.00 42.60      B   MG  

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