>(I've not really followed the thread..)
>How are xyou checking for existing records ?
>If you are using SQL, remember that records
>written to the buffer won't be seen by SQL.

Well, after our procedures, we do an UNLOCK. So, UNLOCK forces a writing to disk. So, in the next millisecond after, that should be seen by other instances of our application running on the same server.

However, now that I FLOCK() instead of RLOCK(), I didn't get a duplicate since yesterday. We'll wait until the end of tomorrow to be sure about the success of that change to be fully sure.