I did not follow you - 回複：Pijiang, xiaobaitu, why my mother's I-

If you meant the I-94 was stamped twice upon admission, it's just an incident and did not have any meaning.

If CBP told your mother not to EOS, better not do so since there may be a note in system. Generally such annotation is on I-94 or visa.

When your mother entered US, she was inspected by CBP (you called it US Customs), not CIS.