As of Release 3.0 you can store incorrect records in a batch-input session when you transfer actual data from an external system. You can then import these records using Transaction KE21 ("Create line items") or correct them accordingly.
You can enter the name of the batch-input session on the selection screen for transferring actual data. The system will store all the incorrect records in that session.
You can import the session under the menu option "System -> Services -> Batch input".