mp_lockanytable keys its control table on (lock_lib, lock_ds), and the
approve service takes that lock on the base table named in the submit
record. The MPE_DATALOADS staleness check is keyed the same way. So two
registrations of one physical file neither lock nor observe each other,
and a second approval can overwrite the first silently.
Spell that out, note that the hook route routes both mirrors to one base
table and so does not have the gap, and give the two ways to close it.
dc