An example would be the PDB ID 2O8A, which fails the sequence similarity check. It looks like the actual molecule has two sets of two chains, but the sequence only lists two chains. Interestingly the _pdbx_poly_seq_scheme and _entity_poly.seq_one_letter_code fields contain the sequence for both chains, though the purpose of these fields is slightly different.
An example would be the PDB ID 2O8A, which fails the sequence similarity check. It looks like the actual molecule has two sets of two chains, but the sequence only lists two chains. Interestingly the _pdbx_poly_seq_scheme and _entity_poly.seq_one_letter_code fields contain the sequence for both chains, though the purpose of these fields is slightly different.