The technical starting position
Complete duplication of a long-term video is costly and complex. At the same time, a crucial segment can disappear if no one knows how and when it should be safely exported.
A backup strategy for cameras involves specific incident images and management, not automatically saving duplicate recordings every minute.

Complete duplication of a long-term video is costly and complex. At the same time, a crucial segment can disappear if no one knows how and when it should be safely exported.
Determine which incidents require export, who decides, who exports, and where the file may be stored according to policy. Check the available recording period.
Create a simple export procedure with channel, time, reason, and storage location. Choose additional backup only when risk, technology, and privacy justify it.
Practice with a test incident and open the exported file on a second device. Verify that time, image, and file integrity are usable.
Not automatically; determine this based on purpose, costs and privacy.
This way it remains clear which fragment comes from which camera and timeline.