Hallo Charles,
the following SAPNotes document this feature:
- 2014148 - Guidelines for Using the Query Result Cache
- 1833049 - Query Result Cache Configuration in Distributed Landscape
I believe in you case you shall take a look at analytic privileges. they can inject a user-specific filter. Caching is applied after this filter was added. Users that share the same privilege, i.e. shall see the same data would also share cache entries.
Regards, Norman