two locks; double locking (bicycle)
Refers to using two separate locks on a bicycle for extra security, a common anti-theft practice in Japan.
When parking your bicycle, make sure to use two locks.
double lock; two-point locking (door)
A door lock that engages at two points, often a deadbolt plus a latch, for improved security.
This front door has a double lock, so it's reassuring.
Wasei-eigo from English 'two' + 'lock', referring to using two locks or a double-locking mechanism.