Hi katia,
Check the exchange rate maintained in Tcode OB08. There may be two reasons for this difference.
1) The rate at which original document is posted is not same at the date of reposting the document
2) The ratio is not maintained in exact decimals. That means if the controlling area currency is USD, system referes the USD rate. It divides the BRL amount by the rate maintained in Tcode OB08. For e.g.
you have maintained 1USD = 1.99999 BLR and in reserve the rate is maintained as BLR 0.50000= 1USD
In this case, if you have not maintained the ratio of USD to BRL in exact decimals, there will be variation in the value which will be derived by the system. If you maintain the ratio of USD to BLR as 1.99 and you have BRL posting as 100, system will calculate the USD value as 100/1.99 which comes to 50.125 USD. Here system does not calculate the value of USD 50 (100 BRL * 0.50000 ) in this way.
Hence, if the amount is big, the variations will be there because of the exchange rate not maintained in correct decimals
Regards,
makrand