This is primarily only an issue when 'zone-statistics full' is in use.

Both the XML and JSON stats produce a copy of the zone statistics for
each view that the zone is attached to.  This is because they walk the
zonetable for each view and emit data for every zone in it.  There is
nothing in either output format that can be used to identify a zone as
shared across multiple views.

The named.stats output produces only one copy of the zone statistics for
each zone by instead walking the list of zones held by the zonemgr.
The deficiency with the named.stats output is that only the "owning"
view is indicated for each zone, leaving no indication about other views
that may also share the zone.

I've attached a named.conf, zone data file, and stats output demonstrating
the issues.