There is no need for separate preservation policies
The objectives for 'long-term preservation' are the same for physical and digital records; there is therefore no need to separate the two. One overall policy, covering both digital and analogue should suffice, as the principle is the same (even though the way we go about it is obviously different). In the first instance, this is about an institutional committment to preserving a collection/archive.
In my mind, preservation is the overarching principle, and other practices, like conservation, may be a sub-heading, not a separate policy (referring also to 2.3).
Why the contribution is important
This will reduce complexity without losing meaning.