Exchange rate variance during voucher match

All,

We are on JDE 9.1. We noticed as of late that when there is an exchange rate variance at the time of matching supplier voucher to the respective receipts, the system is booking the difference correctly to the realized gain/loss account (DMAAI 4340). However, the same difference is showing in the cardex, whereby the unit cost is affected.

Is there a way to avoid cardex updates in the case of exchange rate variances at the time of voucher matching?

Please advise.

Thank you.