Nota Fiscal number

Hello,

We have received incoming invoices twice with same Nota fiscal number (NF no.) issued by the same Vendor. (T code: J1B1N).

This is not acceptable for Brazilian legislation.We have created even in test system posting few invoices (T code J1B1N manually and not from MIRO) with same Nota fiscal no. with same document date for the same vandor. However the system is accepting without any error. This should not happen.

Could any one let us know how this is happening and how it can be rectified.

We are working on ECC 6.00.

Thanks

Lavanya