You also need to assign a new sequence number when changing the date. This will create a new unique record. Then delete the bad record. Easiest way to determine a unique sequence number is export file into Excel, then use the next number. But you may not be able to if you have a bad date.
The fastest way to fix it is if you can export the 10 lines into Excel. Then you could reinitialize the daily posting file. Create a JE and key the 10 lines. Much faster. But you may need to have the full GL number, not just the GL account key.