The fabrics in the upper diagram will not merge correctly because the same zone name (HR) appears in both fabrics and each instance of the HR zone contains different zone members. The fabrics will be isolated.
The fabrics in the lower diagram will merge correctly even though the same zone name appears in both zonesets, because the HR zones contain the same members. If you need to merge two zones with the same name, you must add all the members from Zone 1 to Zone 2, and vice-versa, before you merge the zones.