Hi,
You are facin this issue, because in one of your previous foreign currency valuations, the check box for Balance Sheet Preperation Valuation is ticked. The unrealized gain/loss for that particular run would not have been reversed and is trated as valuation difference in line items.
If you wish to post 5757.06 without valuation difference, then you first need to reverse 4797.55. If you wish to reverse these postings then you will have to reorganize the previous revaluation done with "Bal. Sheet preparation valuatn" option selected.
Create a new Valuation method, in which valuation procedure is "reset" and everything else should be same as the one you are using.
Run F.05 again with this new valuation method (consider specifying your selection criterion to select only those line items with valuation diff), "Balance sheet preparation valuation" should be activated as well. The field BSEG-BDIFF will be reset to 0.
However, you need to take care the FI postings as well. I don't know your scenario enough to suggest you anything here, but I guess you will need to fix the problem which caused the wrong update in BSEG-BDIFF and run revaluation again.
Regards,
Ravi Kumar