Anders Pedersen has a script to determine which backup files are needed to restore a database, but ran into a problem with LSNs matching:
Backup_set_id 1713355 and 1713378 has First_Lsn = Last_Lsn, and they are the same between the two records. There was more records where this was true, just happens to be early in the result set so was easy to spot.
Question then arose in my mind if this caused a problem with the CTE, which it is obvious that it did, but to fix it, I would have to remove those records from being considered in the restore chain (or switch to a loop from a recursive CTE).
Check out the script.