Hi Abderrahim,
There will be two currencies in the GL, Local and Transactional currency. When you see the account in FPL9 it will display the data with two currencies. Now where do you have a problem. At the end of the day 1 Dollar can be either transfered as 1 Dollar or 55 Rupees But not both. So as per your requirement there will be issue in payment runs by doing so.
Hope this helps. 