Panel Connection

I’ve got a service panel with the service wires double tapped at the bus bar. Older 100 amp system with service disconnect on the exterior. Two interior panels; an original and a sub. The sub-panel is not wired through a breaker but by double tapping at the original service connection on the original panel. Are those connections rated for 2 conductors? The wire size looked to be adequate for the exterior 100 amp breaker.

Unless the lugs are marked for multiple conductors they are only for one conductor.

Thanks Jim. That was my original thought but …

If the service disconnect is at the exterior all panels at interior are “subs”.